I had really good luck by buying the soil for my raised beds. I got it from a local mulch/top soil supplier and told them what I was doing and they came up with the blend. So far it has worked great. The biggest reason to go this way is the absence of weed seeds. A year later and weeds are starting to show up but I got one full year of no weeding and to me it was worth it. I can make enough compost to top the beds off each winter so I will never have to buy more soil.

Oh, and I get much better onions by growing them from seed rather than the 'sets' you get at the feed store or garden center. The seedlings look frail and tiny but quickly size up and make huge onions.

meagan , if you plan on siting your raised beds in an area that has wild or lawn grass, you might want to deal with that first and give yourself a wide collar of grassfree area outside the beds. This way, mowing is less likely to spread seeds of grass and weeds up into your raised garden
. If you don't do that first and you have any running grass like bermuda it will establish itself under your raised bed
and erupt amidst your veggies. Then, it's nearly impossible to eradicate.

I would also add that plenty of the plants on your list don't need super rich, premium soil. Some of them are picky about soil in a mild way - you'll get better carrots if the soil has no lumps or clods and is extra fluffy as deep as possible. Onions perform better with lots of organic matter worked in - I think you could grow them in solid compost. Tomatoes and peppers will grow a lot of leaves but not a lot of fruit if the soil is too rich.