Getting a low cost conservatory is not that difficult, as long as you are already prepared for the general expense that comes along with doing so.
It must be said, however, that if you are thinking of just spending a few hundred pounds on a new conservatory, then you are more likely to get a DIY greenhouse than a room you can comfortably live in.
Most low cost conservatories will cost a few thousand pounds. Professionally fitted basic Conservatory rooms at 2500 mm x 2500 mm size, will come in at starting prices of £2500 and upwards.
Really speaking, anything smaller than a 3 x 3 conservatory (meters) will be cramped and difficult to really enjoy with a family.
But, if you are on a budget, maybe you can try to get an ex-display model from a conservatory installer showroom.