Suggest a best air cooler for my small room

As you are telling it is a small room, I suggest you use the air cooler of the model Smphony Kaizen Jr.
There are other models which are good. But they may be more helpful for big rooms.
Symphony DiET 12T is another model which can be used in a small room.
Some other models are Bajaj Frio, Cello Swift, Crompton ACGC-DAC555, Symphony Touch 55, Symphony HiCool and Usha Honeywell. But you have to select the small model which will be useful to you in small rooms.

Some of the factors that you need to keep in mind while selecting coolers are :
- Blowers : Blower type air coolers work effectively only for small to moderate rooms as they dispense air in a specific direction whereas fans are ideal for large circulations of air in bigger rooms.
- Things in the room : If you have many items in the room, it will add to the heat. The more open space, the more cooling it will get.
- Proper closing of room : It is always good that you have proper sealing of the rooms as it will help in fast cooling of the room.
- Ventilation : Kindly see to it that you have ample circulation of air in the room.
- Cooler type :
a) Personal air cooler - Used for cooling of small to medium size rooms
b) Desert air cooler - Used for cooling of medium to large size rooms

Keeping these in mind and as per the question raised by you, I would suggest the following :
1. Jk electro appliances jkrc09 Personal Air Cooler
2. Crompton Marvel PAC201 20-Litre Evaporative Air Personal Cooler
3. Bajaj Torque PX97 36-Litre / Digital DC2015 43L /Platini PX97 36L /Icon DC2015 43-Litre
4. Symphony - Ice Cube 6.5/8.5 kg, 105 Watts Air Cooler/ Storm 100i 270W / Hicool 31L / Diet 12T 12 L Tower Air Cooler
5. Cello Smart 30-Litre Air Cooler
6. Usha Honeywell CL601PM 55L Room Cooler
7. Kenstar 15 L Tower Air Cooler with Remote
8. Maharaja Whiteline Blizzard 20 L / Thunder+ 20L

For a small room there are many models available in the market having prices within Rs 10000. I will advise you to go for a reputed company like Bajaj , Crompton , Hindware or Symphony etc. If you buy from online stores like Amazon, Flipkart, eBay then you can have good discounts also.

Please note that you should have an open place like a window or a door towards balcony against which you have to keep this cooler otherwise it will heat up the room and make it sultry. The placement of a cooler is very crucial.

Some of the models which I can suggest are -
1. Crompton Desert Air Cooler (75 – Litre).
2. Symphony Hicool Air Cooler.
3. Maharaja Whiteline Atlanto+ CO-110 Air Cooler.
4. Symphony Diet 12T.
5. Hindware SNOWCREST 85-H Desert Air Cooler.
6. Crompton Optimus 65-Litre Desert Air Cooler.
7. Bajaj Coolest Frio Air Cooler.
8. Bajaj Platini PX97 Air Cooler.

As you said it is for a small room & the mentioned budget is Rs. 10000 and should run on the inverter. Let me tell you one thing, the room should be well ventilated & cooler should be installed in a window outside the room for better cooling of the room. Unless you have an air circulation you will not be satisfied with air even if you buy a cooler at a higher price.

List of Air coolers under Rs10,000 & Inverter technology
1. Bajaj COOLEST FRIO Room/Personal Air Cooler (White, 23 Litres)
2. Bajaj Platini Coolest Torque PX 97 Room/Personal Air Cooler (White, 36 Litres)
3. Hindware SNOWCREST 85-H Desert Air Cooler (Lavender, 85 Litres)
4. Crompton ACGC-DAC751 Desert Air Cooler (White, Grey, 75 Litres)
5. Symphony Diet 12T Room/Personal Air Cooler
6. Bajaj Coolest PCF 25 DLX Room/Personal Air Cooler (White, 24 Litres)
7. Flipkart SmartBuy Polar Tower Air Cooler (White, Black, 47 Litres)
8. Alpine Tower Air Cooler (White, Blue, 30 Litres)
9. Bajaj COOLEST TC 2008 Tower Air Cooler (White, 26 Litres)
10. PHOLOR COOLER ARCTIC AIR Room/Personal Air Cooler Room/Personal Air Cooler (Multicolor, 0.75 Litres)

This item number 10 is a personal (very small) cooler which has got good reviews, one of my friends is using now & said about it. The cost is also very less around Rs. 1300.

When buying a cooler for a small room, two things are more important, first, how small is your room, and second, what is the arrangement for ventilation. Because the room is small, the coolant will also give more, but if proper ventilation is not there, the hot air will remain in the room, and in such a situation the coolness of the cooler will not be felt. Nowadays, many types of coolers are available in the market, which is small in size, but you will get other facilities as well.

In the cooler, an ice chamber is now coming up. When it is hot, fill ice with it. Cooler water flows through this chamber through the motor and continuously cool air remains in the room. From turning the cooler on and off via remote, the speed of the fan in it can also be more or less, turning the motor off or on, etc. Honeycomb pads not only last longer than wood wool pads, but they also make the air very cold.

Now there are coolers with technology that work on inverter technology. There is a sensor in it. When the room gets colder, the water motor in it stops and the fan speed decreases. As room temperature rises, first the fan speed increases and later the pump turns on.

Some good quality and low price coolers are below, you can buy these coolers online as well -

1. Thomson cpd70
2. Kenstar HERCULES-RE
3. Voltas Grand 72L Desert Air Cooler
4. Symphony Kaizen 122 DB 21 to 30 Personal
5. Kenstar GLAM 50I Air Cooler
6. Voltas Mega 60E 60L Desert Air Cooler
7. Bajaj DC 2015 ICON Air Cooler
8. Vego Empire 40 40L 150W Tower Air Cooler
9. Usha CCL70PE Desert 70L Air Cooler
10. Clarion LG-15 Longer Air cooler