Here's some thoughts on this:
Because of the difference in price between a TxP pack and a regular booster pack, $5 vs $3 (or $2 or $1, but who uses prophets and UL?), this would suggest that we only do 1 TXP pack. Here's what the math looks like... (I'm using market value. It will be comparable even with host discounts)
If you did 1 TxP pack:
half a starter- $5
1 TxP- $5
Total: $10
If you do normal, 3 boosters.
half a starter: $5
3 boosters: $9
Total: $14
Now, here are a couple other options.
If you do 2 TxP packs (this will drive up prices for registration a little bit)
half a starter- $5
2 TxP- $10
Total: $15
If you do a TxP Pack + 1 booster
half a starter- $5
1 TxP- $5
1 booster- $3
Total- $13
Actually, the final option is my favorite. Why?
1. You can get a booster from a set not represented in TxP (Kings, Preists, AW)
2. It evens out the price best from a host's perspective.
3. There won't be a million and one rares floating around.
Now, here is my opinion though: If you are going to include TxP in your sealed deck, it should be all or nothing. Either everyone gets a TxP pack, or everyone gets 3 boosters. I think the playing field would tilt too much. Just my 2 cents.
~Marti