I don't think there is a premium to these. They are also very easy to fake. I'd pass. Unless they are silver and you can get them for less than melt.
Packaging errors aren't considered true errors per se* (and can be faked) and usually have no premium or very little (like $1 to $2 at most over what it otherwise would sell for). Is interesting though. I've seen proof sets and uncirculated sets where they accidentally left out the nickel and put two dimes in the set (in the days of cellophane packaging, which applies to proof sets 1964 and earlier, and was true of uncirculated sets until rather recently). Get it if you like but don't pay much more than what a correctly packaged set would go for. This "error" isn't worth much (beyond what the coins would normally go for). (*Well OK, it is an error in the sense of an unintended mistake, but it's not an error in the numismatic sense, since there's nothing wrong with the actual coins.)
This was a nice scam back in 1999. When the proof sets first came out there were a bunch of reports of "error" set missing one quarter and having a duplicate of one of the others. The "error" sets were bringing over $600 on eBay. Up until 1999 the proof sets had been sonically sealed, but the 99 sets could just be snapped open and closed again without a trace. So scammers were buying five regular 1999 proof sets for a round $250 (due to order limits prices for the sets were high), opening them, playing musical quarters, and then closing them again creating five "error" sets that could be sold for $3,000. There was a variation of the scam in 2000 when "special VIP 10 piece 1999 proof sets" started appearing on eBay and selling for over $1000 each. Take one regular nine piece 1999 proof set ($25, prices had come down) a 2000 proof set (About $18) and a 1999 P proof SBA ($10), remove the 2000 coins from their 10 piece holder and put the 1999 coins in. Put the holder into the 1999 box and sell on eBay as a VIP set for $1000.
