Its very hard to know value of cars. Any car, but always in the end, it's what somebody is willing to pay.
The "somebody" looking for a Bellett is a rare breed, unfortunately, which means competition to buy a car is likely to be very low and hence prices. And then on top, one must re-build the car too.
I just bought 2 Bellett Sports (2 door sedans) models for less than that figure of $5200, out of Japan, although, shipping to Australia will be additional, like out of Tassie will be to some extent. But they are rare Bellett models, none here I am aware of. Maybe I paid too much also, as the market to re-sell a Bellett is limited. But, I AM afflicted with the 'disease'.
The market is most likely the people on this group in fact. And even then, probably only those that post reguarly.
glenn
I started a web page on my Sports which I will update every now and then.
http://www.carnut.info/bellett/my-belletts/SPORT/Bellett_SPORT-72.htm