Okay, for all those wondering about earplugs for djing, I got a pair of those expensive custom ones today. I've been getting some tinnitus lately, and I've been concerned about my hearing. I'll give these things a review for those who are considering getting a pair. I was honestly very pleased with them.

The initial fitting of the earplugs had to be arranged at a local hospital. They jammed cotton far into my ears, which was a little uncomfortable, and then poured in some mold with a scringe. The mold hardened after about 10 minutes, and then was removed. I was then showed the options of what I could get. Mainly, for musicians, there was the ER-15 and the ER-25. The ER-15 cuts 10 decibels and the ER-25 20. They cut the frequencies evenly, unlike traditional earplugs, so they sound the same, just at a lower volume. Guessing from my experiences from parties as to the volume level at them and what I've heard other people say about the decibel level of parties, I opted for the ER-25. They were $180 US. (I think the ER-15 was about $110). I then had the selection of material, and I chose latex over vinyl, as it was supposed to be much more comfortable (the other option was for those allergic to latex). They also had the option of the style of them. There was standard, countersunk, and semi-countersunk. The countersunk ones had the filter surrounded with a latex donut, designed to fit into the grooves of the ear. I chose standard (though for whatever reason, the doctor ordered countersunk later). The doctor told me to schedule a pick up time in a week.
So today, one week later, I went back in to pick them, suprised to get countersunk ones, but not particularly minding it. I was shown how to insert them by the doctor and was able to converse very well with hear while they were in. Her voice did not appear distorted, just quieter.
I took them home and decided to try them out and see how music sounded. Listening to music at standard volume was very quiet and sounded a little louder than a whisper. I took out a pair of headphones (Sony MDR V-6's) and decided to test how much volume it took for my ears to become uncomfortable. I turned my cue level up to max (usually I listen to the cue with the cue volume knob around 1/3 or a little more turned up when I'm mixing at home, which is kind of loud, and I listen to less than that when listening for pleasure). I was surprised to find this at a very even, non-intensive volume, perfectly reasonable and didn't hurt my ears whatsoever. I could hear the synths and highs very well, and overall there was little distortion. I next turned up all the levels on the channel +12 dB. This was somewhat uncomfortable on my ears and sounded about what a club normally did. I then went back to the monitors to test them and see how much it would take to hurt my ears. I was surprised to find that even with my amp all the way up, it was still tolerable to my ears, though now a little bit uncomfortable (the bass still felt a little rough). The track came in with very good clarity though, seeming about equal in frequecies, with the bass maybe a little heavy, but this was at the point where you could really physically feel the bass pretty well. (I stood about 3 feet from one speaker and 8 from the other while testing). The amp is 200 watts, with each speaker's max at 120 watts.
Next I tested the ability to mix. I took 2 tracks (Katana - Dulce Vita --> Eon - Pocket Damage, if it matters). I turned the speakers up to about what I'd heard at parties standing a few feet from the speakers, and the bass from my speakers began to distort a little (as my carts are very bass heavy). None the less, I was able to beat match fairly well between the two tracks, directly in front of the speakers, with a little distortion of the highs from the massive bass. My ears were pretty comfortable throughout the whole ordeal. The only problem I had was this the disorientingly distorted bass, but that's from my cheap ass $40 speakers I got a pawn shop. The bass is not nearly as distorted in real life, and you wouldn't necessarily be directly in front of it.
As far as how comfortable the earplugs are, they put a little pressure on the inside of your ear, but not painfully at all. They measure about a little less than 1 inch long (2.6 cm). They seem to stay in your ears relatively well and I could not get them out by throwing my head around and jumping up and down (pretty roughly, at that.)
Aesthetically, they are a little noticable in your ear, but for what you're getting out of wearing them (your hearing for another 40 years), I'd consider it worth it.
They came with a one year warranty.
All in all, I'm quite satisfied with them, but they may be a little costly for some of you out there ($180 + the fitting expenses).

DJ Nuclear ~_^