First of all, new unlocked iphone could go as high as almost $1000. If you buy it locked and with long contract, you just re-paying "credit" during contract which costs far more than I would spend on mobile communications otherwise. Since OpenMoko ppl are not going to apply operator lock, it's not an option for them. The only non-locked iphone worth of $100 is iphone 1 or 2 generation which would hardly beat that omap as well.
So you have to pay full hardware price at once. No discounts and credits. But what's good results from it?
1) It's not locked to any operator. It's yours, not operator's. So you can choose operator and plan yourself. As it always has been in GSM/3G designs.
2) No DRM (restrictions) crap as well. So you're owner and phone obeys you. And not going to make harmful actions you could dislike. Isn't it good?
3) It haves clean system design, not HSPA modem centric at all, unlike many other designs. It's a computer and HSPA modem. Amount of harm it can do to you and your data on remote requests are limited. Other phones may contain really unwanted activity like
RRLP, backdoor-style misfeature. Sure, it's declared for use in emergency but you see, it's possible for governments, staff and others to (ab)use this feature for very accurate position tracking. Lack of such features could be a good idea and once cell modem have to rely on Linux system controlled by owner, it's easy to keep under control who can use GPS and when. On some other phones it could be much harder. For example, on Qualcomm, modem is a core of system and can access everything. Including GPS. On a proprietary firmware will.
4) It's not restricted in boot loaders so owner can boot anything that is able to run on this hardware. Isn't it nice to have such option?
Basically, it's phone for owner and developer. Not a phone made to keep media mafiaa guys happy. Not a phone to make cell operators happy with their lock-ins. Not a tool of vendor to enforce their dictatorship what to do, what you can and when. Unlike many other devices. Sure, this device is not for dumb iphone users who abandoned their privacy and consumer's rights in favor of glamorous crap. But it's still haves it's niche.