Originally Posted by Andy_K

That's an interesting suggestion. It could save money, but BSOs are notorious for their use of non-standard parts so I would expect a lot of incompatibility. On the other hand, if you pick the right BSO it would be both cheaper and better than the Free Spirit plus Tourney parts. The OP could even completely disassemble the BSO and put it back together (adding grease where it was missing!), which is usually a good idea anyway with those bikes.