Assuming you're still learning, I highly advise keeping the rubber bands. Rubber bands do a great job saving airplanes. It's not obvious at first, but after I built and crashed a few, I learned that wings are incredibly strong (considering their construction). What frequently happens in a crash is the wing tip hits first. If the wing is solidly attached to the fuse, the weight of the engine whips around destroying the fuse between the engine and the wing. Adding the flexible rubber bands uncouples this. That's not to say that you can't destroy your plane if the wing is on with rubber bands, but I believe it saves you in a lot of crashes.

If you go to a bolt on wing, what most folks use is plastic bolts, on the theory that the bolts breaking will do the same function as rubber bands. The problem is that plastic bolt strength is tough to estimate, and they aren't consistant. Also, unless your plane is designed for it, it's tricky converting a plane to bolt-on, and some crashes are caused by the conversion failing.

By the way, if you're worried about the cost of the bands, instead of buying them at the LHS, buy them at Staples.