What's a fair price?

Next up is aquilegias. Most of the packet germinated so I have quite a few of these left to shift , even though they've been quite popular so far. Selling them for £2 per pot or 6 for £10. They were originally in 6 cell module trays, but the heavy rains over winter compacted the compost so much I didn't want to sell them like that, so I moved them into into 9cm pots.

What potting medium do you use, TMTT, homemade or bought? If homemade what recipe?