I want to sell my car and will of course try to get the best price I can, but at the same time one has to be realistic so my question is if the insurance value of the car is a good asking price?

Look at union-auction.com. There are some pricelists you can download (scroll down, at the calendar on the right), that should give you some overview of the market for used cars.

Insurance value is not usually a realistic market price.

Better to look at the various S/H sites like Talarod, Baht&Sold, ThaiVisa Classifieds etc.

Compare similar cars to yours and see what they're asking price is, then price yours accordingly.

Depending on how competitively you want to sell.

^This, auction price is oft times beneath wholesale.

Look at union-auction.com. There are some pricelists you can download (scroll down, at the calendar on the right), that should give you some overview of the market for used cars.

You mean the same auction prices people on here are recommending because of the excellent bargains available?

I would not buy a car in an auction. I would not buy any used car here without extensive checking as they are usually completely run down. Not sure where you see an excellent bargain here, other than indicative pricing. Auctions are actually full with all the failed financing from Yinglucks populist "first car" tax scam. You wont get more for an old vehicle.