I spotted a RazoRock Black Hawk for sale not too long ago and received it yesterday. It's inexpensive (I paid £30 including about 15 Feather blades). Gave me a great shave yesterday but is exceptionally light which I'm aware isn't to everyone's tastes.
Buying new, you'd have to buy from America (
ItalianBarber.com) but they're currently out of stock - with the exception of the satin silver version. I contacted them about a week ago and they said they're anticipating more stock within 4-6 weeks.
If you're happy with a silver razor, it's a cheap way to try out a SE. I specifically wanted the black! If you work it out and add VAT and Duty charge of ~£8 and postage at circa $15, it still works out at about £45, which is roughly half the price of the offerings available here.
Alternatively, check out Executive Shaving's offering of the Claymore Razor
here. It retails for just short of £70 without postage, or you can pick up one which has slight manufacturing defects for £46.50, again sans P&P.
Whatever you plumb for, you're going to be able to recuperate most of the costs selling them on, especially if you bought second hand in the first place!
Hope this helps!
Edit: I've definitely focussed on modern SE razors in this post. The suggestions of injectors or Ever-ready's are more than valid!