Well I wasnt even aware of sizes. What I did was buy a starter propagation kit that included 50 peat pellets and a dome. It was onlt 10.00$ which would be under 10 for you since I assume your on the pound. These pellets are aproximatley 1.5 diameter. If you are going into soil I dont think the size really matters ( thats what she said) The peat has everything a seedling needs to get them upto size for the transplant, no chemicals needed. Im not a soil guy so my knowledge is limited. Let us know how it goes and what you decided, dont kill yourself over deciding, just buy some and use them. They are cheap.... Hope I helped cya