Anthem Five E2 is one of the most affordable Custom In-Ear Monitors on the market. It is a hybrid design that includes a low-frequency Dynamic Driver and a high-frequency Balanced Armature Driver. It will cost you $199.
Fir M5 is a flagship IEM by Fir Audio, that's based in Vancouver. It is a trybrid design using 1DD, 3BA and 1EST drivers per side. Here's a review of the custom version with ATOM modules, costing $2948.
Craft Ears is a polish company that makes hand-made IEMs. Four is their middle model, and the custom version you'll meet in this review costs 580 euros.