for example, instead of the $ 29 per Realtrack set, why not 'upselling' them, i.e. also combining packages of more Realtracks or even customizable ones at a lower price? I think the buyer would spend more than $ 29

I just bought BB megapak and at first I was just getting the PRO version for budget issues, but now that I have tried out the Realtracks I 've got for the extra 70 bucks, I am pleased I went for the Megapak version. I'd like to get a few other Realtracks too, they are really nice