Just to add a bit of nuance, "pure" usually means ONLY taking te and/or pots, not a "mix" that might include cards and/or te/pots.
Pure = no cards,
Mix = cards+te/pots,
Trade = just card(s) to card(s).
But I have seen a lot of people use "mix" to mean just a straight card trade, which makes no sense to me lol.
Usually the pure price is below what the mix price is, because unless the seller needs or wants the cards that the buyer is offering
, they then have to turn around and sell those cards, and are taking a risk at holding additional cards. Where if they got pure, they can then go a buy whatever they want in that price range. So if the buyer is offering a mix, and not responding to something in particular that the seller wants, the buyer will usually need to add overall value to the transaction.
All that being said, I've been in the position of seller several times where someone offered me an even card trade (same value) and I took it because I liked the card I was being offered, so it might not hurt to try
But other times if I don't want that card I will say "can you add a little" to indicate that I'm not keen on that particular trade, but I'm willing to do it if they add value for my trouble of needing to flip their card for them.