HJE 900 best for <100$

Hippo VB for a bass-head.

IE7, Custom 3, Turbine, EX700, FX500 and HJE900.......

The HJE900 should be in that list. Unless you mean you want to be able to find them inside a physical store? In that case you will probably only find them at J&R in NYC. They are currently only 89.

If worn over the ear especially, they stay perfectly put in my ears. Using foam tips further secures them. I always work out with them.

From pretty much all accounts I've heard they sound better than the S4, at least. I haven't heard them compared to the others. Mine certainly sound very good for the price.

It might depend on what you mean by bass head.  Some people want a lot of midbass and like that emphasis.  Others simply want good extension and the ability to actually produce a 30Hz or 40Hz tone.  Sometimes the emphasis is done on some headphones because the extension isn't there.  Are you looking for emphasis?  Extension?  Or both?

One I will toss out there is the Denon ATH-C751.  It isn't talked about all that much on the forums as of late, but it's an excellent earphone and one with a solid bass line.  The Custom 3 was already mentioned, one of my favorite bang for the buck earphones around, very good sound quality, a thicker note that is unusual for balanced armature drivers.  It does roll off on the bottom end though but has solid bass presence otherwise with the thicker note.  Plus it responds well to EQing, so a little bass boost can get you what you want.

There are a number of earphones specificially known as having good bass, and some of them have already been mentioned above.

Your needs seem to be very similar to my own.  Unfortunately, I have all but given up on finding any of the better IEMs physically in stores regardless of price range.  After looking at common shops, such as Fry's, Best Buy, Target, etc, it is apparent they are stocked almost solely with the likes of sony, low end jvc, coby, Dr. Dre, bose, and skullcandy.  The only respected brand of IEMs that seem to be carried physically in stores are shure....at least as far as brand and model go.

If you are leary about ordering online, as I am, I would suggest buying Amazon gift cards so you don't have to worry about credit card theft and then you can order from them with some sense of security.

Keeping in mind that my needs are in the same physical use vein as your own, here is my current list of "most wanted" $100-$200 IEMs:

1. Jays qJays

2. Panasonic HJE900

3. Senn IE8(used)

4. Radius DDM<--I'm pretty sure these won't work for running though.

Okay if you are a serious bass-head, and I mean serious, then the most tremendous woofer in the head earphones I have ever heard are the Audio Technica CKS70's, which are like being punched in the ear. I'd suggest given your budget that you look into the newly released upgraded model the CKS90, which is apparently a bit more balanced. I don't know how well they will fit in the ear running, but they are a hybrid canal/earbud design which may give you some clues.

The DDM's are definately the kind of sound you want (really good sound in fact) but I don't think they will be a good option for running at all, just in terms of comfort and microphonics.

Whatever you choose, you definately want something with a dynamic driver rather than a balanced armature driver, since really only dynamic drivers at that price point can move enough air to give you that subwoofer feeling. This includes the S4, DDM, IE8, HJE900 - but not the UE 600 or d-Jays. You also want something where the earpieces are light weight, since the heavier they are the more likely they are to fall out while running. 

Sorry I can't give you one specific recommendation, but I hope that helps clear things up.

Have a look through this thread, you're going to find something good here:

http://www.head-fi.org/forum/thread/478568/multi-iem-review-105-iems-compared-phiaton-ps210-yamaha-eph-50-pioneer-clx50-added-09-08