I reacon the only way you could possibly do one is if you have a mate who is stainless or fabricator, get one of them too price you one up I bet it would be the same price. Also it come down to its there, its all you will ever need and it will last a life time.
The keg alone to buy is at least 60 bucks at a scrap yard, 3 piece SS ball valve would be about 50ish, the SS dip tubes would cost you probably 40 - 50 to get made, glass lid would have to be about 30, 1/4" NPT thread would be about 15, similar windshields on TM are selling for 35, give the guy 2 hours to build it at 60/h and that totals = 355.
Considering a 50L pot will set you back around the $200 mark, for a thin walled SS version, this with all the bits isn't a bad deal.
On a side note, my 3 kegs (without therm, SG or valve), 85L pot, 65L pot, 35L pot, 20L pot, 2 immersion chillers, a plate chiller, a sanke false bottom and maybe a few other bits and pieces will be up for sale soonish when I get my shit sorted out.
i suppose it depends how you look at it, you can build it yourself a lot cheaper,it only needs basic diy skills.
mine cost
5 kegs 3 as keggle and 2 as fermenters, $45 each $235 all up
march pump- trade me- $100
camlocks& tubing- about $180
copper, ball valves, manifold etc-still had change from $150
immersion chiller- roll soft copper, trade me- $60
elements-trade me- $25
glass lids-warehouse $10 each
the table was being binned so i rescued it, cables etc were an old extension lead.
i pretty much went straight from extract to all grain and built it so i have no gear that i've moved up from and is now unused so i spent roughly $800 for a complete setup, if i ever decide to sell it then i'm sure i wouldn't lose on it
of course it could be even cheaper, a pump isn't necessary, no pump then camlocks aren't required, thats why i thought $350 was getting up there;)