Posted: 05/02/2013 at 13:07
Have found whilst researching that polycarbonate greenhouses deteriate with age, so could potentially be more expensive in the long run, as will poly tunnels. That said, if you're not planning to live at your premise for a long period, then it might be worth getting a cheaper poly tunnel or polycarbonate greenhouse as you can simply dispose of it and buy another one at a later date.
With regards to glass breaking easily, I understand that that's a genuine concern where money is not available, so standard horticultural glass is provided, but I've got mine from greenhouse direct (Rhino harvester) and it has come with 4mm, single pane, strengthened safety glass. The idea being, that if it were to break, which would take some doing even at 3mm thick, it will shatter like modern car and bus windows, into tiny granular like pieces. This does cost, but that said, I'm in for the long haul and think that with 25 years of guarantee as standard, it's worth it. Again though, if I were going to move in 3 - 5 years time, I'd go polycarb everytime as it's just not worth the hassle of having to dismantle and re-build. There is one obvious downside to this thinking, and that's environmentally, it's very much a disposable method and I can see why many would think this senseless.