If you have a co-op nearby you can do it yourself. BB will be around $25, chain around $15, freewheel about $25 but more likely to be a cassette for less. Watch Nashbar for a deal on chainrings, I think these would fit and they go on sale for around $10 every so often - includes both rings.
http://www.nashbar.com/bikes/Product...29_-1___204711