Aldi are advertising on their recent brochure (not on their site) a greenhouse for €19.99 - description as follows:
Steel tubing construction with removable, transparent, tough durable PVC cover with two front zips for easy access and ventilation. Easily assembled with push-fitting joints, no screws required 125 (h) x 69 (w) x 49 (d) cm, with three shelves connected by plastic connectors. Can be used with their seed and cuttings tray and triple propagator pack.
The model Sueellen described from Aldi is excellent! My garden is the size of a postage-stamp and space is at a premium and I've propagated and hardened-off all my plants in this little greenhouse. Is very sturdy, nice-looking and has the advantage you can move it about easily.