I go to Perfect Prey for all my rats. mice and chicks. I'm still looking for a good rabbit provider even though 2 large or jumbo rats are less expensive to feed than one rabbit. I just like to offer a varied diet to my critters. If your retic is eating 6-8 mice per feeding I'd get a mixture of medium and large rats. The medium rats at Perfect Prey are 90-150g each and the large rats are 180-279g each.

https://perfectprey.com/