The cheapest option is TLTC for sure. BBTS is similar to TLTC on Hasbro products before shipping and without GST. I have not used BBTS in years so I'm not sure what shipping will be like compared to TLTC for the same amount of items, but it will be higher since TLTC charges a flat $15 per order.
BBTS has always been a bad choice for Takara products because you are paying import into America. HLJ, NY, etc have always been the better choice for Takara.
My quick back of the napkin math says before shipping BBTS will be similar to slightly higher than TLTC on Hasbro products going forward.
But keep in mind not everyone is confident in TLTC. Some people think they are the next PC. That said I use TLTC for much of my TF shopping. They have been in business for over a decade, they just need to communicate better as to shipping delays. I've always gotten what I ordered from them.
But BBTS has impeccable customer service on the other hand so it might be worth paying that little extra to use them.
I'm trying BBTS for the first time in years with my POTP Wave 3 preorders. I'll see how things go.