craigslist for a carpenter/sheet metal worker or general contractor in your area and have them build one for you. finish with a 4' x 8' (at least) cutting mat and you're set!
+2!
I found a local guy on ebay (who turned out to be a 17 year old carpenter's apprentice) - he was cheap, professional, and extremely happy to be making money while learning what he loves doing.
Was a definite win/win.
I was surprised how good his attitude was at that age, and how much initiative he showed for doing what he was doing when I see so many other kids his age doing a lot less.
He talked me into a formply top, which was worth the extra $ IMO - you should get something which can take a bit of water in case you ever have a big run of wet app panels or for whatever reason.
The final product was an 8x4 - with castors, so it can be moved around if required. It also has a shelf under so I put a lot of stuff down there and save on storage space too. It also has a full coverage cutting mat on top, which is a must IMO.
I had another long bench made at the same time, around 2x8. Same, with castors and shelf - this one is used just as a long bench, if we need to mount to large panels etc but most of the time it's just used as a table for outgoings and a bit of packaging storage etc, as it's near the door.
For both benches, which were custom sized, he charged around $500, which I thought was very reasonable.
True, you can build one yourself for not too much hassle... but when you're working and have other stuff to do all the time, and can't afford the dust in the same room as your printer... all worth it.
Good luck!