Phials are usually worth 1m-3m depending on the buyer and how desperate he/she is.
Tengus are 20m-30m, mostly because Stewart/Maid pets are very similar, and can be bought for astros/are also better looking. Well, that and the fact Tigers/Wisps are way in more demand than Tengus.
Pet chargers are 9-11m OUTSIDE of Auction. If you toss it up for 13m in the AH, it'd be bought eventually. (See: people being desperate and/or too lazy to find it outside the AH)
4 Leaf Mics go for 600k-800k.
Gota sets, as most function sets, go for 15m-30m. You could easily sell it for 20m, though. It really depends on how many of X sets are up for sale and how many other popular ones are up for sale. (Peeps go for the popular ones first, and then the cheapest versions of your set) Just check around the player-store area and AH before tossing it up for sale.
"He who fights and runs away, lives to fight another day!"