It's okay... a lot of cheap ferts have a large portion of their nitrogen coming from urea, which is slow release (okay) and can also burn your roots (not okay). These off-the-shelf ferts can do well - I would suggest using 1/2 of the lowest recommended dosage at first.
You can still get good ferts with better nitrogen (nitrate and ammoniacal) and better micronutrient profiles without blowing the bank -- Jack's and Dyna Gro make good stuff without urea, and still cheap -- you'll have to look a little harder or mail-order. Foxfarm has good stuff, a little pricier and gimmicky-er, but still good. I think the "super duper bud booming blaster budz" kinda stuff is BS at a high price, but I'll admit I haven't used any of them, that's an IMO thing.