Stark Brothers is having a pretty great sale currently on a LOT of stuff.  Strawberries is one of those things.  They've got a couple varieties that are $5.99/25 pk, some that are $8.99/25 pk, and some that are $9.99/25 pk.  We currently only have one smallish strawberry bed with no more room in it, and I'm wanting to take advantage of this sale.  They're bare root plants, so what would be the "best" way to put some up until I have a few new beds ready to go?  Honestly, it will probably be near Fall before that is done, since everything else is in full swing right now.  I've got hundreds of pots of various sizes and nursery trays that I've saved over the years.  I'm thinking I could pot a couple hundred plants up and plant them in the early Fall soon enough for them to get established enough to overwinter  (zone 6B).

My main question is:  how small of a pot could I realistically get away with, in order to keep potting medium usage down and to keep the footprint of all of these trays to as much of a minimum as possible?  Any advice?  Is this a horrible idea in general?

ETA:  Guess I could include a link to the sale, for anyone interested

https://www.starkbros.com/tags/spring-inventory-sale?s=Price:ASC

IMHO, you can't hold bare root strawberries that long w/o problems.

You're on the right track with pots. 6" round would be ideal. You may get away with 4" but you will probably stunt growth, setting them back a year.

Good advice.  I'd prefer to do square 4"s but I don't want to do so at the expense of stunting them.

OP may not have a local place but he should definitely look into it.

An Amish greenhouse local to my parent's sell their bare-root strawberries for $26/HD regular price.