To answer the first question "Would I buy a pre-made and pre-painted set of boards and terrain", the answer is yes, I would.
However ...
Would I buy them if they were going to be roughly $200-300 (circa £100-150 quid), then the answer would probably be no simply because I dont believe for one minute that anything of a half decent durability, quality of finish or build could be made, retailed and delivered for so little.
If Mongoose can source boards that meet the qualities most of you have cited as being required for under £200 (say $400), then I would be frankly amazed. If they can be done that cheaply then I suspect they will not be the sort of boards I would be interested in buying.
A good costing example would be someone like 'Warscape' in Scotland. Sadly I think they may have gone out of business now, but they were producing vac-formed plastic 2' x 2' table sections such as hills, rivers, swamps, etc. These were unpainted and generally untextured, but were a great idea. They retailed I believe at something like £20-25 a panel so a 6' x 4' table would cost £120 (roughly $200) not including delivery.
Although strong plastic, being vac-formed they were far from rigid and as I say, were un-textured and un-painted. For something of similar or (hopefully) better rigidity than what Warscape produced, plus painted, packaged and delivered I'd say I'd be prepared to pay somewhere circa £300+
If we are talking a bit of filler over some waste polestyrene to keep the costs down then, no, probably not. That I can do my self.
If Mongoose can source them cheaper without compromising the build quality then kudos, but I wouldn't be surprised if even my estimates were optimistic.
With Warscape seemingly vanished, I'd say there was definately a market opportunity there for the taking if you can come up with the right product.
Regards
Carl

However ...
Would I buy them if they were going to be roughly $200-300 (circa £100-150 quid), then the answer would probably be no simply because I dont believe for one minute that anything of a half decent durability, quality of finish or build could be made, retailed and delivered for so little.

If Mongoose can source boards that meet the qualities most of you have cited as being required for under £200 (say $400), then I would be frankly amazed. If they can be done that cheaply then I suspect they will not be the sort of boards I would be interested in buying.
A good costing example would be someone like 'Warscape' in Scotland. Sadly I think they may have gone out of business now, but they were producing vac-formed plastic 2' x 2' table sections such as hills, rivers, swamps, etc. These were unpainted and generally untextured, but were a great idea. They retailed I believe at something like £20-25 a panel so a 6' x 4' table would cost £120 (roughly $200) not including delivery.
Although strong plastic, being vac-formed they were far from rigid and as I say, were un-textured and un-painted. For something of similar or (hopefully) better rigidity than what Warscape produced, plus painted, packaged and delivered I'd say I'd be prepared to pay somewhere circa £300+
If we are talking a bit of filler over some waste polestyrene to keep the costs down then, no, probably not. That I can do my self.
If Mongoose can source them cheaper without compromising the build quality then kudos, but I wouldn't be surprised if even my estimates were optimistic.
With Warscape seemingly vanished, I'd say there was definately a market opportunity there for the taking if you can come up with the right product.
Regards
Carl