Good soil is the key to good production for pretty much everything. Find out what the farm makes it's compost from (yard waste, leaves, animal manures, etc.) and how long they age/turn it. You don't want raw manures (burn plants), or a lot of lawn clippings from chemically fertilized yards, etc. I'd call your local extension office or a college ag department if there is one, and find out if they can do a pH test of your soil and/or nutrient tests for cheap. They will advise you on amending the soil and also might have insight into the compost you're preparing to buy.
Personally, I'd start small (space wise). Make a list of what you'd like to have, then use some library books to help you see what kind of space you need. Remember that some things can be planted in succession. (Peas will be done early and then you can re-use the space, for example.) Better to do well with a small garden than have it go to weeds or struggle trying to do too much.
Budget some money to buy some plant packs of the more difficult things to grow yourself, or things you only want 4-6 plants of. Personally I usually buy broccoli and cauliflower because it takes a long time from seed and I don't have optimal indoor locations/light for seed starting, and I'll buy one each of an eggplant or specialty pepper, etc because we just don't eat a lot of those and I don't need a pack of 100 seeds, etc.
Plan to plant easy-to-grow things directly into the garden, such as peas, beans, radishes, lettuce, zucchini, cukes, herbs like basil, flowers like marigolds or sunflowers.
Experiment with starting some medium difficulty things yourself, such as peppers, tomatoes, but leave a little money in the budget in case you don't do well.
As far as money, budget for seeds, seed starting materials as well as hardware and supplies for the garden, like a hose or trellis materials if you can't find or make freebies (last year I wove a stick trellis for cukes, and we scrounged free bamboo for bean poles and staking, but I do own nice steel pea trellises that double as tomato cages when the peas are done).
I think the biggest pitfall with garden spending is going shopping in the spring without any plans at all. People buy a whole bunch of stuff that "looks good" but then either have the wrong conditions or don't have the time/energy/space to plant it and weird expectations of how it should grow. You sound like you're on the right track starting to plan now.