With the economy the way it is there are many people that would love to have the advantages of a greenhouse but do not have the money to invest in an expensive glass or plastic pane greenhouse. It's not that they do not want to get started growing as early as possible or extend the season as far into late fall and early winter as possible, it's simply a matter of money!
So for those who are financially challenged right now, I have a few ideas that you might kick around and see if any of these are capable. The first thing you can do is see if your community or city has a garden collective or co-op where you can garden, in other words, work in the greenhouse or garden and for that work, take home some of the food. This can not only be a great way to supplement your grocery list but you also are helping others.
Another way to get something going is to form a small co-op in your neighborhood and raise money to purchase a greenhouse so you can grow food year round. You will need to form this with trustworthy people and make sure the greenhouse is located on neutral ground, if possible so everyone can access it. You will also need money for water and heat so you do need to be prepared for these expenses. This can be a great way to add to your food source.
If you are not crazy about working with others in a co-op situation but would like the opportunity to grow with a garden greenhouse there are some very inexpensive greenhouses available. They will not be as sturdy and most likely will not last as long as some of the more expensive homes but they are good enough to last through several seasons in most climates.
Of course, use you head here. If you live in the Artic, these greenhouses will not do well at all. If you live in a semi mild climate and need to start seedlings early to get a good growing season or would like to extend the growing season into late fall, this might just be what you have been looking for. Most are also portable and can be used on decks and patios as well so measure and make sure they will fit before you order.
The basic lesson is if you really want what a greenhouse can give you, there are products on the market that could work for you. We all have certain things to overcome and, if the budget is your thing, there are decent green homes out here.