I have been playing 
An Achievement That Took A Long Time
It was one of those pleasant surprises to come across during gameplay. Rewards like this can provide good positive feedback fro long term players. The content of the Booster Pack was not anything amazing or wonderful. I have already experienced good luck with Seasonal Mission.
A Elfy Dose Of Christmas
I think this should be "An Elfy Dose"; but I am not very hung up on it. Let's call it artistic liberty. There are two Cards that can be earned playing the game. Aside from the market value, the Cards have gameplay utility. I have seen that each of these Cards increase the maximum Skill gained through Music Lessons increase by ~1. This is based on anecdotal observations.
S49 Christmas Bagpipes
S50 Christmas Drum
Despite only having a slightly lower supply, S50 Christmas Drum has 2.3 times the market value compared to S49 Christmas Bagpipes. Out of the two Cards available, I would find more utility for S50 Christmas Drum myself. The most preferred instrument would be a guitar. I will have to wait for a different Seasonal Mission to start earning those.
Total Market Value
- S49 Christmas Bagpipes are worth 45,200 STARBITS
- S50 Christmas Drums are worth 78,000 STARBITS
Combined value is 123,200 STARBITS. At the current market conditions, that can be traded for 5.00808 HIVE. Since I did not have to buy S48 Christmas Elf Card, all these earnings can be treated as having infinite ROI. Even if you consider the 10,000 STARBITS investment into purchasing the Booster Pack where I found the S48 Christmas Elf, there is a 1132% ROI.
STARPRO Requirements and STARBITS Millionaire
It is highly recommended to have some STARPRO if you are completing STARBITS Millionaire Missions. There is no good reason to leave out a 10% bonus. STARPRO can be earned through Music Promoter or they can be bought at the market. The minimum amount of STARPRO needed to become eligible for 10% bonus increase as you play more Missions.
I have been doing many Music Promoter Missions and I have more than enough STARPRO. I have decided to sell some of the extra and invest in HIVE which is easily one of the most underrated and overlooked sleeping Behemoths of cryptosphere!
If you have time for another HIVE DAPP, you can check out the game and start earning. The gameplay is mostly consisting of managing timers and working with tokenomics of the game. Best of Luck!