I paid 30$ CAD for my 83 nishiki. 100$ is nearly a third of the cost of a bd bike. Your going to need to buy a new wheel set. Re lacing the wheel plus the cost of the hub will cost roughly the same as a decent 700c wheel set. The current 27" wheel set makes your tire choice limited if you would keep them. You'd most likely want a different saddle, long reach brake and cross lever for the 700c wheel set. bar tape, foot retention, labour if you cant do all the work yourself or have the tools, cog, lockring. The cost adds up little by little if you can get the bike for 20$ go for it otherwise it will most likely cost more. If thats no big deal convert away! I found that my conversion was a great learning process but like tohers have said it's not for everyone.