What is it worth to you? What other candidates are you considering?
I am with two tired here. Quit beating yourself up on this one. Bike looks good if it started and went around the block its good to go, you can work the kinks out a little at a time.
The price is irrelevant if you like it, buy it. Like everything, it is worth what you paid for it.
Its your time, your hobby, the knowledge you acquire taking it apart and putting it back together. That is worth the real $$$. Buy it and have fun. If it does not work out, put a Little TLC in to it and sell it. Here is the plain truth below... If you check out Ebay that bike is priced pretty fair.
Motorcycle Valuations
Prices of older motorcycles can vary enormously depending on a variety of factors including location, condition and provenance.
In order to assess the value of your bike we suggest browsing sites which specialise in the marque in question, for instance owner's clubs and dealers. Searching auction sites and classifieds is also an excellent source of information about vintage motorcycle prices.
The following sections of the Bikelinks directory will get you started.
Motorcycle Auctions
Classifieds
Clubs
Classic Motorcycle Dealers
Ebay Countries has links to many of the country specific Ebay sites.
Nada Guides has a section on Vintage Motorcycles
Redbook Australia covers many European, collector's and classic motorcycles
bikesales.com.au/tools/valuation.do