A problem I've noticed whenever I come back to Lorwolf is that the mole market's recipe offerings make game progression punishingly difficult. Options for apparel and tool recipes always seem to come from the same pool of low rarity/early game recipes, often recipes that I already have. Maybe low rarity being more likely to stock is intentional, but due to the small number of recipes in stock and how infrequently the market restocks, the odds feel nigh impossible to get higher level tools (ie Mithril/Lorium/Chaosium/Gold wheels and pickaxes) and thus I'm hitting a point where further mining progression feels impossible (or at least would be incredibly frustrating and slow).
I think it would be a good idea to have recipes stock based on what you already own, so recipes you already own won't be filled up the limited stock space, and to give higher rarity recipes a higher chance of stocking based on your mining level (and thus ability to use those recipes).
Edit: I agree with what other's have said that recipes stocking based on what you own should be a weighting towards recipes you don't own and not completely blocking out recipes you've already acquired. Also that expanding options to improve chances would be good.
I also just want to say that I don't want it to be so easy someone can get high level recipes in "a few refreshes", I just want it to not be impossible, which from my perspective so far, it is. I have yet to, even once, see these higher level tool recipes in the mole market OR flea market. Having a hard time getting a recipe might be part of the game, but never getting it is just turns into not being able to play at all.