Hi Bekib86,
It really doesnt matter that you dont have a lot of money, something that has been thought about is much nicer to receive than something that cost a bomb.
Depending on what sort of relationship you have you could do the following and it wouldnt cost you a penny...
Create a voucher book with 'sexy treats' on each voucher, ie foot massage, romantic bath together, make his favourite dinner or something a bit more kinky!
Or you could just do something more romantic for him on the day itself, just think about what you would like for valentines day, if you too like the same things, chances are, he will like it too.
If you want to buy him something it really doesnt have to be big, most valentines day gifts are only small. Have a look at shops like clintons, etc for gift ideas