In my opinion for the prices that some places charge it's not worth it. I saw one site flogging what they claimed to be a hi-tech grow box, they showed a pic of how well it's concealed in a room, etc. However upon examining the pic you could see that they had purposely lowered every object in the room so that you couldn't notice how small this shitty thing was. The pictures on the wall were lower than a nearby window and the bed was just a mattress on the floor. Don't get me wrong, you can grow great short plants but I wouldn't fork out the £1100 that the company was asking for this micro grow box.
If the price is right go for it, but if it's expensive as hell it'd be cheaper getting someone you trust to help build you one.