$400 is carquip pricing and is what a retailer that is a known source can charge as they store them.
I usually sell them for $200 a set, but as mentioned there are sets on ebay that have been less so my prices are always negotiable. Prices for me factor in 3 things:
1) How much it cost me to acquire it from parting out a box (boxes with X gears in them are usually $400-750 so selling them at $100 a set will not cover the cost)
2) Market value - I cant sell squat if someone will sell it for less.
3) How bad I need the $$.
So, $150 is not unreasonable if you want it gone. If you want it gone sooner, sell it for less