What size ballast you are looking at? The cheapest ballast is 2x32W - you buy a T8 shoplight that has an electronic ballast for around $15 (from HD & other hardware store) & take the ballast from it.
Another source is to check out the Fulham workhorse ballasts - they are the ones used in AH Supplies' kits & people have good luck with them. They can be found on the net for $20 & up (depending on size).
PS - you usu. can't break the ballasts, it is usually the lamp holders or wires that breaks ... before buying the ballast, check that one of the wires had not come off the lamp socket, & the socket is not cracked, etc. These cost much less to fix.
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.