I agee. They are crazy priced on eBay sometimes. In the Netherlands we have www.marktplaats.nl That is better. But the site is in Dutch. You can also ask repair-bas If you need one.
Because ebay has a huge international market to sell stuff on the prices go up to redicoulus heights. If you are looking for something rare make sure you check within communities such as these to find it but stay away from ebay.
As mentioned allready: your sources, repair-bas, hondamsx, daniel and there are some more sellers active on this forum that have fair prices.
I did that mistake, that I purchased an MSX2 thru Ebay. Should have asked here first. Luckily (?) the postal services partially smashed the unit, so I have a reason to return it, or get some compensation. The machine works, it just isn't so pretty anymore...