Good idea, but I think it would be better if:
You get a pack that is either 10k, 50k, or 100k. There is only those levels. All items within are no-qi. With the 10k pack, you will most likely get items that are cheaper, but there is a very rare chance that you could get even the most expensive items. (Ex. void force- 0.5% chance). In the 10k pack, there is like, 3 items.
The 50k one has 5 items. The chances of getting better items is increased by a certain amount, and the chances of getting low teir items (ex. marine relax) are lowered. It's worth much more, but the chances of wining are higher.
The last is 100k. It has 7 items. The same rules apply.
There is no guarantee of winning any high tier items in any packs, but there is no guarantee of winning low tier items.
Alternatively, you could have a part of the shop labeled "Slots" where you pull a lever on a slot machine and you can configure the amount of TC you put in. The more you put in, the higher chance of getting good rewards there is.