I would not pay more than $300 all-up for a SP20 at this time, and would be hesitant at more than $250.
Even that would depend on my geting moved VERY soon to a very cheap electric-rate location (which isn't happening as soon as I hoped).
I wish you would use actual pricing instead of " I would not pay more than". Look at ebay lots of sales but it is going to be mid to high 300's to 400 as a general idea.
Miner's do not sell for what we wish they would sale. They have a cetain value. If you did the " I would not pay more than" at your prices you would have no miners.
As it happens, I haven't bought any miners for a while - as I see ZERO chance of anything current achieving RoI before the halfing and pretty much NOTHING current except perhaps the S7 for a short while will be profitable at all after tha halfing, per my current projections.
If actual pricing is higher than I am willing to pay to achieve a REASONABLE CHANCE OF ROI, that just means most of the market isn't doing projections of RoI based on what I class as reasonable projections, or possibly some folks have a TON better electric rates than I have - or the most likely cause, inertia leading to failure to adjust pricing to what is really fair by current standards.
There is nothing new about "market pricing" being higher than reasonable. or price adjustments being slow to respond to external changes, or a market going with "optimism for the future" instead of paying attention to current conditions.
Try watching the Dow Jones over the last 5 years - crazy high levels of stock price increases while the economy as a whole is barely recovering from the Great Recession and most corporations are NOT actually doing all that much better overall.
Mining right now is lower profit than it pretty much has ever been, BTC pricing has been edging up lately but NOT enough to match recent difficulty increases - and the only reason diff increases haven't been higher for the last month I suspect to be the shipping delays BitMain has been having on the already-sold S7s.
Your opinion may vary. Do not fold, spindle, or mutilate. etc.