I was thinking of reshelling my TF10 but I figured that I could also buy the cheapest UE customs.
How do they sound compared to the TF10? Better? Worse?
Well the UE4 is a dual armature compared to TF10's triple armature. Personally I think the TF10 is a great IEM and with the exception of the muted mids (which some people may or may not like), and based off the impressions of others they're probably better than any other custom in the same price range (~$300.) You might want to look at other, more competent top tier IEMs rather than a low end custom as you have to be dead certain you're going to love the sound signature of a custom, as there's no going back (without incurring large losses.) Seeing as you already own the TF10, if you like the sound signature then by all means get it put into a custom shell. Otherwise I'd recommend looking for a more competent universal (not that the TF10's aren't already great.) Oh, and according to my friend the mids get brought forwards a little by a reshell.