Who to sell bulk gp to?

As term starts, It seems to be inevitable that sythe becomes less active and my sales drop like a rock.
I get a fair amount of orders, but a lot are under 50m and it takes a serious amount of effort and time when you're trying to sell bulk gp in under 50m/trade.

So in the past 3 days I've been looking into known gp shops and their rates, the best price I was given was .52 and the worst, .3 [Which I didn't even consider]

I pretty much need some advice, when it comes to experience when dealing with gp shops outside of sythe.
Your opinion of the most trusted, legitimate and helpful, and the ones to avoid at all costs. If anybody else has sold to a gold site and could give me the ropes, that would be great.

I'd gladly sell to grave, but I think his rates are too low, [unless he decides to buy @ .5]

Thanks in advance