Congratulations for making you set.
Vegetable Patch puts Luxury pile in Kingdom but is better without them. If you simply ignore Luxury cards, you have a Lost City at $4, which is broken.
The card itself is better without them, but is your game better without them?
I think so.
- Luxury cards: Cost $5. At first play they are stop cards or don't draw. Each one gives a vanilla bonus at start of your turns:
- A free Copper every turn, not so good.
- Fair effect, which with Fair costs $4 and is imediately activated.
- Barracks effect, which with Barracks costs $6 once and is imediately activated.
- Hireling effect, which costs $6, but Hireling is stackable.
- Vegetable Path, ignoring Luxury cards: Cost $4. Gives two vanilla bonus at each play (card and action). It's Lab + Village. It's stackable. It's not difficult to play every copy you have in all your turns if you have some of them.
This would be different only if Luxury cards are the only source of +Buy on Kingdom, but even in this situation I think I problaby won't go for them.
Lost City is a $5 Card with a penalty on gain, because it's too strong to be only a $5.