Read the size of the tires on the bike now to get the size of the wheels. Your bike probably has 27 inch wheels and you can go to your local LBS (or the web - Nashbar is a good place to start) and buy F+R aluminum wheels. If cost is a real issue your LBS can order wheels with nutted axles rather than quick release - which would be the next step up cost wise. I don't know that wheels with nutted axles can be gotten on the web easily. I think I paid about $40-50 each for complete 27 inch nutted wheels with a freewheel type rear hub from my LBS.

The better option if you can would be to put a new set of 700C wheels on the bike. To make it work the brake shoes need to move down about 4mm (about 1/6 inch) to accomodate the slightly smaller radius of the 700C rims. If there is enough slot on the brake calipers to do this then you will have a LOT more options when choosing replacement wheels. If you go the 27 inch route you have basically one size to choose from - 27 x 1 1/4. If going 700C then a 700 X 32 would be an equivalent size and would look right and ride well on the bike.