A couple of glitches with the Item Mixer:
1) Mixing three items of the same type, colour and level gave me an item of same type and colour, but a lower level!
2) The cost of mixing items of different levels varies dependent on the order the items are selected in. Selecting the highest level item last gives a much greater mix cost than selecting it first (around 15% more expensive).
3) Un-selecting items in the mixer breaks it. Put three items in, then take one out, and the cost disappears. By randomly† taking items out and putting them back in again, it is possible to reduce the price to nearly 50% of what it should be.
I’m enjoying the game and it’s always nice to see developer interacting positively with the gamers.† It seems random, I haven’t identified a sequence that works every time yet.