I'm building 4'x8' raised garden bed to grow tomatoes, lettuce, herbs, etc. and so far I bought a bunch of top soil for cheap, but now I'm thinking I need aeration and amendments. So my first question is what type of aeration should I add in my garden soil? Ideally I'm thinking perlite but that could be costly on a garden bed that big? Any other alternatives that are much more cost effective? Second is that I heard those compost you buy at Lowes/Home Depot are junk; mostly made up of compost leaves and mulch which I heard is low quality. So I looked up some on Craigslist, but the places that sell worm castings/compost manure from a local farm are like an hour drive away. Any other alternatives to this that could be cost effective and as good as compost/manure? Thanks in advance.