ebay for a kinesis.
i've had 4 kinesis i got for around $50 each with shipping, they were all arguably new and minorly used or never at all. The secret truth is that most ppl buy a kinesis and stop using it or give up after a few days, cuz well it takes time to relearn how to type, this means you can usually get in on a deal.
here's my pro-tip for buying em, usually now you'll only (99% of the time) find white kinesis on ebay, look at the wrist rests, make sure they are NOT stained, or basically make sure that it's one color, no one in their right mind will go and buy replacement pads (cuz they cost 50bucks anyway) just to sell their kinesis.
Of course you might come into the problem of people that have already replaced their worn pads (cuz of use) or there aren't any pads at all, with this i just look for another kinesis.
look, you have no options, you mentioned you would like a TE or a kinesis, but you have a budget of half the cost of a new one of either model, all other so called mechanical ergo keyboards SUCK, so don't bother.
and of course hoggy has a point, if you want an ergo board, then you're in pain, either get the kinesis, with my ebay way, or get more/extra cash, don't let your wrists become nasty old woman 55year old haggard witch secretary hands.