Hi Wilson,
If you have found that BIAB is valuable for you, I encourage you to get the UltraPak. This has all Realtracks except those few that are provided in the bonus material (e.g. 49Pak). Eventually, these bonus Realtracks seem to find their way to later UltraPaks anyway.
Even though the UltraPak will give you tracks that you might not use, it certainly works out cheaper because there will be so many tracks that you will use. Also, PG Music, have a 30 day money-back guarantee and it's worth asking for your RT package that you recently bought to be credited against the UltraPak if you decide to go this route.
In 2006, I bought the MegaPak. Once I'd played around, though, I knew that it was worth getting the best I could afford. At that time, it was the UltraPak. I've never looked back since.
To keep the UltraPak updated with new Realtracks, Realdrums and MIDI Supertracks, it costs around US$100 each year -- if you buy when the Christmas sale is on. This is the PlusPak upgrade that's available for UltraPak owners each year.
At the moment, it looks like the MegaPak 2019 to UltraPak 2020 upgrade is US$279.
I hope that this information helps.
Regards,
Noel