There is none out there. so I don't know what would be a good price for this

I'd say 5mil would be a fair offer for the item, since Dog Treat Dispenser is at 5mil right now in the Shop Search

I've seen a lot of monthly gift items in shops for 4.5mil, but as Novae said, if the Dog one is 5mil, you could price it there and just watch the price.