Light Wattage?

I have a question about lighting. I was most likely going to going to go with a HPS lamp setup. I am probably going to only have 1 to 3 plants at a time in a small grow area. I was originally going to go with a 250 W lamp, but the more I read about it I thought maybe a 400 W would be worth the extra cost. If the grow area would be around 2 x 2 at most, would the 250 be good enough or would I need to spring for the 400. Also do most lighting stores carry these types of lights and setups for them and around how much do they cost on average. Thanks for any info.

the 250WT will give plenty of light in a 4'sq-ft area(62.5WTs)....bonbon

[I][COLOR=Navy]this place has the lowest prices that i've seen to date....bonbon http://www.1000bulbs.com/category.php?category=878

Thanks a lot. I was having a hard time deciding. That will end up saving quite a bit of money over time. I thought if the yield would be greatly increased then the extra money would be worth it, but I thought it might not, so thanks. Thanks for the site too. That is a ton cheaper than I have seen on all the other sites I have checked out so far.

http://www.1000bulbs.com/category.php?category=878