Setting up my tent help

Hey guys looking for some advice and a little help if possible. I recently purchased a 2x4x5 grow tent. The next thing im going to be buying is a grow light. Now the tent is fairly small so I dont plan on a big garden, mabey 2-3 plants tops. I was looking for a 250 watt mh/hps switchable system on amazon and ebay, and happened to find both a 250 and 400 watt system for close to the same price. 250 watt is $125 and 400 watt is $135. I will be setting up my tent close to my window which has a ac unit in it. So my question is would I be better off just getting the 400 watt light for only $10 more? Would heat be a issue being as the tents not too big? I will have a fan in the tent and the ac unit by it will help. How much more in electric cost will it be about for the 400 compared to the 250 about? Lastly is 400 too much for that small of a tent and only a few plants?
Thanks in advanced.

you might want to look into a 400 watt cool tube. it may be perfect for your grow.

bump. still need questions answered.

If you are talking about the Hydrofarm switchable ballast hood, don't buy it for your circumstance. Go with a cool tube. I own that hood and for that small of a space it will put off WAY too much heat.

As far as the power, it is preference. I would go with the 400 for more growth. You can figure your cost by dividing the wattage of the bulb by 1000, multiplying by the hours of usage, then multiply by your cost of electricity per kwH. (For example: 400/1000= .4 .4x18=.72 .72x30= $21.60/ month) That example is at $.10/kwH on for 18 hours.

Hope that helps. If I missed anything let me know and I will help you out.