The old Casascius brass are hard to find in good shape. Back in 2011 was Casascius coins not really collectibles yet - and bitcoin was only worth a few dollars, so these was carried around in pockets and passed around. Not too many of them was kept in mint condition, this is one of the reason why there are not many old high grade brass in circulation.
If you have an old Casascius brass coin and it is in pristine condition then would it be worth grading it for sure.
Edit: This post pretty much sums up Casascius premium value back in 2012:
Theres a day in my life Ill never forget.
I had a roll of 60x 2011 error coins, back in 2012. This was back when Bitcoin was around $13.
These coins were literally hanging around our office, on everyones desks, we'd give them away, throw them around, whatever
We were moving offices and for some reason I peeled off the hologram of EVERY coin and redeemed the private keys I dont know why I did it. I may have been in a mood to condense my Bitcoin into 1 spot and I literally sat there for two goddam hours redeeming those coins.
I felt so satisfied after, like 'Yes, now my Bitcoin is all in a wallet together'
FML