What socks said, except that I would just buy a "name brand" second hand recumbent and go from there. Look on the BHPC/CTC/YACF selling sites and eBay. Avoid something with no name as it could be uncharacteristically rubbish and will probably not sell on easily. Something more expensive will probably be easier to sell than something less expensive (e.g. if you buy a bike for £500 you would need to be practically giving it away second hand, whereas a £1,500 bike you could sell on at £500 less than you bought it for). Consider also the cost in time/effort to go someplace and look, then return and buy.
Expect that your first recumbent will be a starting point for the wishlist of your second recumbent, hence why thinking about resale value is important.
Also, depending on your size a highracer may be tricky to start on if you need to learn to get your feet down. Possibly a 20" front wheel will make your life easier there.