(This should probably be moved to another forum besides bottom feeders)
YAY! 30 gallon is a good size, have fun with it! I would look in the newspaper classifieds and at garage sales. I don't like buying stuff new because its just so dang expensive. I'd rather get a used tank and be able to spend more money on the stuff that goes INSIDE. I got a 15 G with a stand at a garage sale for 18 dollars. I suppose if I was looking for a 30 and a stand I would probably pay 50 dollars depending on how good everything looked. The other option would be to find a used tank and then get the stand from petsmart because their stands are pretty reasonable.
Heater would cost between 15-30 depending on how good quality you get. I think you need a 100W for a 30 Gallon tank (someone correct me if thats wrong)
Filter would cost about 30 -? depending on the type/brand you want. I think the run of the mill power, hang on the back filters that do 300 gallons per hour are probably around 30-40 dollars...but you might want to upgrade that, totally up to you.
Don't know much about sand, I'm going to put some in my newest tank. but from what i've heard/read/had suggested to me sand from home depot...just normal play sand works just fine.
As for fish...totally depends what you like and whats available to you. You could have a great community tank with maybe some mollies and swordtails, a couple of bottom feeders, some danios, some tetras. Or a 30 would be big enough to put an angelfish and a school of smallish type fish (not neons) and a bottom feeder.
I'm jealous
have fun!