After Auction Pricing

A condominium went into auction at a minimum bid price of $90,000 (reserve price unknown) and did not sell.  Later this property that did not sell was recently put on the market for $180,000 two months later.  Developer is trying to sell other units as well.  Is there some "rule of thumb" as to proper initial offering price might be?  Thanks for any info, I just don't want to "over-offer" as a buyer, if the price may go down further later (it's November now).