No, I use pots. I've seen other vendors use the newspaper cups, but they kept falling apart before the customers could buy them. I have a feeling that your soil blocks would also.

I use used ones that are sanitized, and accept used ones back from customers.

Most of my plants are sold in 4" pots, good healthy starts since most customers(mine) aren't too experienced in taking care of the smaller plants.

BYOP, bring your own pot!
I have never heard of anyone successfully doing this. Maybe full flat custom grown, but transportation and moving of them to and from a market would be a nightmare. How many are you wanting to sell?

I agree that soil blocks are just too fragile to make the trip - I would invest in recycled paper pulp pots or those cowpots I am seeing in the catalogs this year and build the cost into your pricing.

I agree with the other posters here,plant starts in soil blocks would be too fragile. I have seen coir pots 3-1/4"x 3-1/4" 1540 pots for $163 at the Greenhouse Megastore online could be one option.

I re-use the cell packs whenever I can. A lot of people save them, and many of those people will be happy to return them to you so that they can be re-used.

I have sold lots of soil block seedlings. i put them into a used plastic shopping bag for the trip home. If a person buys many than I find a flat box to put them in. I have never had any complaints and a lot of return customers who like the idea of less packaging.

Thank you so much to everybody that responded. I really appreciate your thoughts and ideas. I'm going to look into some of the things you suggested and see if I can find a supply of boxes that would be deep enough to keep the plants protected. I haven't had any issues with the soil blocks coming apart as I've handled them because the roots keep it all together. I'm hoping to sell hundreds... :)

For boxes, I always check my Sams Club out. Some of the boxes that previously had Strawberries, Peppers or Tomatoes worked for me.

Be sure you have any permits you might need. In Indiana, you need a Retail Merchants Certificate and collect sales tax.

I put a box at the front of my booth for recycling small pots.

I use the flats that pop and beer come in and you can get hundreds by asking at any place that sells such products.

I have found that soil blocks do not come apart easily with a 5+ week old plant in them.

I like deeper boxes than the beer/soda flats, that way I can stack the boxes without hurting the plants.