I noticed limited edition silk screen covers when launching new LP-s compilations.
Great idea, and I would recommend adding as many of below:
> Doing significantly different artwork on the front cover as well (noticed back changes).
> Adding a limited edition poster or 7" with the order
> Stamping "limited edition" on the cover and the label
> Having a unique label (even "blank" is better than using the mass produced one)
This would not necessarily command a premium, but I guarantee it would enable to sell more limited editions, faster (providing more "reasons to buy")