I've only recently started shaving with a straight, so perhaps I can give you my point-of-view:
It wasn't at all clear to me that I'd get on with shaving with a straight razor. And an expensive razor that has been in the hands of a complete newbie is likely to fall in value at the same speed as a car. So buy your razor like you'd buy a car that you might want to sell on soon after purchase: Either buy a brand-new cheap one (eg. Dovo best quality from Steve) or buy a nicer, but "used" one from Neil (or another trusted seller). Don't go for a highly-sought after one (like a NOS Dubl Duck) or a brand-new expensive one.
I don't buy the argument that a newbie is more likely to ding a new razor -- I am paranoid about damaging my razors and I expect most sensible newbies are the same. I expect to get more careless as I get more confident and carefree with shaving. (Just like you stress over touching a new car, but having owned it for a few years come to accept the scratches it inevitably gets.)
However, I do buy the depreciation argument, and I also realise that I am more likely to blunt a razor through incorrect stropping resulting in the need to send it for rehoning a few times. I don't really want unnecessary hone wear on a "favourite" razor.
As for buying them; Neil seems a straight-up guy and should be a reliable place to get one (<!-- m --><a class="postlink" href="http://www.strop-shop.co.uk" onclick="window.open(this.href);return false;">http://www.strop-shop.co.uk</a><!-- m -->). However, his stock has been quite low since the beginning of the year. The "bargain" section is probably the best place to get one from. But there's nothing in there at the moment. I'm afraid I don't recognise any of the names in the "vintage" section, so can't advise which one is best to get from there other than the usual advice (ie. 5/8-6/8, 1/4-1/2 ground, round point). Steve also has some restored vintage blades on his website (<!-- m --><a class="postlink" href="http://www.theinvisibleedge.co.uk" onclick="window.open(this.href);return false;">http://www.theinvisibleedge.co.uk</a><!-- m -->) but again I don't recognise the names.
The other place I would recommend is looking in the classifieds section on <!-- m --><a class="postlink" href="http://www.straightrazorplace.com" onclick="window.open(this.href);return false;">http://www.straightrazorplace.com</a><!-- m --> Look for a seller with good feedback, or find one with some history on the site and read their posts. You can usually tell quite quickly which of them know how to look after a razor. Bear in mind that irrespective of what you pay to a US seller, if the razor is only "worth" £18, customs won't be worried by it. With the exchange rate what it is at the moment, you could get a good bargain.
EDIT: £18 is $28.87 for March using HMRC's exchange rate.
