The price you payed for it seems resonable. Never pay $100 for instructions, you can get them in PDF format on the Internet for free. Great work and hope to see an MOC from you soon.
Yeah, it would be hard to pay that for instructions, I personally don't have them for the set, but would like to get them to complete it. I just got back into Lego this last year after my son got a Lego set for Christmas '10, and I got hooked again after not even looking at them since I was about 13(a long time ago ), so I missed out on the first 3 mods if you include Market St as one. Probably spent about $3000 this last year on different lines of Lego for me and my son both to mess around with. Sold my old ones for about $750, so that helped curb the price. My wife thinks i'm crazy, but I really don't spend money on other things like video games and such, so there was plenty of money to feed this (now) addiction.