The domains if you order them through the site are only 1.5btc.
If you register them yourself with a namecoind it looks like they are 0.03 NMC (0.015 name_new and 0.015 name_firstupdate). That's about 0.00012 BTC per domain. I don't think I'd use the registrar and pay 1.5 BTC if I was going to buy that many.