1) You can pay someone about $50-75 for a title search, if you don't want to do it yourself...
2) Good condition Tank would be ~$50 on e-bay
3) Try and start the thing as-is. You may be suprised. I bought a bike that had been sitting in an IL garage long enough to get a medium-sized yellowjacket's nest under the license plate (fortunately there were no yellowjackets inside when I got it, just the abandoned nest)... All it needed was a carb cleaning ($3 for a can of cleaner, and some time) and a battery, and it spun right up...
Those old bikes are boneheadedly simple - 2 carbs, 2 coils, 2 plugs and either a points ignition or a real simple, non-adjustable electronic system (1st-gen electronic ignition)...
They're also real hard to break, and you can get boat-loads of parts off eBay for next-to-nothing...
If you want it looking good, not just running, you're looking at a tank, 2 side panels (you're missing the plastic side-covers), and possibly a seat...
Probably $300 if you use E-bay, and it will be looking/running good...
The folks saying 'It's gonna be expensive' are all assuming you will be using new parts...
If you use e-bay parts, you'll be just fine - you can get good condition tanks, VERY good seats, and such, very cheap... I got a seat for my Suzuki 450 (1982) for $30, in like-new condition off E-bay... Carbs - complete sets - can be had for under $20... Pretty much everything you need, you'll find there, most in the 5-50$ range...
If that fails, then go to www.ronayersmotorsports.com with the mfr P/N... They have VERY good prices on new parts...
www.bikebandit.com has the parts diagrams online, and for some bikes (Suzuki), they had the MFR P/Ns listed. They are, however, VERY expensive, so I just used their part-finder to get the part #, and bought from RonAyers