How long is a piece of string?.
Anywhere from £50-100+
Like i said, Ive just paid £35 for a viv thats half a foot smaller than that size. Personally though, I'd say a tank like that would be a bit big for a baby.. Especially just settling in. The critter keepers may be plastic, and not the most attractive thing to have in your living room compared to a nice, fancy tank. But atleast the snake would be comfortable in it, It's a cheap solution (Though not as cheap as tupperware boxes!) - I found it to be easier to heat that the glass viv aswell.
Exo-terra vivariums could be an alternative.. but for one that size your looking at £65+.