Personally, I wouldn't hunt down any particular razor, but instead keep an eye on ebay and the classifieds here, until you find something you really like and that is good value for what you get. ie. I ended up buying a couple of 7 day sets... wasn't actively searching for them, but stumbled upon them and acquired for what I thought to be a very fair price. You'll probably find like I did, that you bid on plenty up to the limit of how you value the item, loose a lot of auctions but be very happy with the ones you win.

ie. A W&B anchor sold recently on ebay between 200-250. Add some $ to have restored with scales/wedge to your liking, and you have a relatively rare, brand name razor tailored to your liking. I did the same with a slightly larger anchor not too long ago, gssixguns is restoring for me and building lignum vitae scales and brass wedge, will be a stellar razor for around or under the price you mentioned.

Alternatively, the custom route would be great, but you need to know what you want. I would imagine that if a custom was what you were after, you wouldnt be posting this question.

Finally, there's always the Robert Williams SRP limited edition. If there are any left, that would be a viable option. With the input of so many experienced and knowledgeable members, and Robert building them, I imagine it would be hard to go wrong.