mjohns2, As grey said jeans and a T-shirt will do, but there is all types of hunting gear out there, you need to know what kind and color trerain you are hunting, here is a link to Cabelas , they have it all and some good deals, just look for there specials on all types of jeans to cammo. I myself have all types of cammo for all types of terain, but thats what I prefer. Good Luck
Budget you say? Check your local Army surplus store, even Goodwill or the Salvation Army. Swap meets also. Loose fitting but durable. Lots of pockets for carrying lots of unnecessary crap. Trial and error is the way to go, everybody differs in what to pack along, same with clothes.
I agree witht the Cabela's boys. I buy all my stuff from them. Even stuff I don't need. If you just started off hunting varmints I am sure you will keep moving up to bigger and better things so you might want to buy some king of camo for all types of hunting.
I would suggest you go somewhere you can see the clothing you will be buying. I hunt in the southeast and pay particular attention to how quiet the camo is that I will be purchasing because we hunt close to our prey here. I also like a blend of cotton/polyester since it tends to fade less and is pretty durable. There are some better materials available but most are expensive.