Gridseeds cost ~$150-200 per 1 MH/s even if you buy them used on eBay. With Innosilicon A2 rigs at ~$120 per MH/s and 1/3 the power consumption of Gridseeds I think the writing is on the wall. One thing Gridseeds still have going for them is the granularity, i.e. you can pick one or two for what basically is pocket change on ASIC scale. A2 starts at $3000-$4000. So for someone looking for a hobby / science project buying a gridseed and overvolting the hell out of it could be a good cheap entry into mining.