Cold frame thingy

Just bought a plastic greenhouse from argos you know the realy cheap one for about £50, what a load of rubbish, total waste of money. That will teach me to do things to quickly and cheaply. The thing is i cant afford a decent greenhouse so would it be just as good if i made a sort of coldframe thingy and use corrugated roofing sheet or polycarbonate twin wall sheet for its roof and walls. Proberly a real stupid question but i just dont have a clue, any guidance would be most readily accepted.
Many Thanks in Advance

I you're not fussy what it looks like, just build a cold frame from old window frames. I got some off freecycle and then built a box from pallets so that they would form a lid.
Even an orange box with a bit of plastic over the top would be OK - or get a polystyrene box from a chinese supermarket or fishmongers and put some plastic on the top.
I think they are as good as greenhouses, cost very little and can be used flexibly. They are also very tempting to cats who want to sunbathe.

just keep trawling the internet..i got my 8x8 for £20 (about 8 mile away from my house too!) just before Christmas...so there is deals to be had...you just need to hunt them down