If Obidiah was working with the Ten Rings then why would the ten rings need Stark to build them the Jericho missile? They could just ask for a shipment from Obidiah.
Maybe Stane was asking too high a price (as opposed to simply capturing the invetor and getting him to build it for free). Or perhaps Stane, despite his mercenary ways, nonetheless wanted to retain a tactical edge (for instance, his little death-pen). Or, again, perhaps having such a high-profile weapon turn up in the hands of insurgeants would cause too many questions to be asked, as opposed to the more conventional weaponry Stane was selling. Fictitiously yours, Trent Roman
Because Stane wasn't supplying them with that kind of tech at that point; he just hired them to kill Stark and threw in lower-level ordnance as a price (hence, why the Ten Rings later send him a message demanding additional payment in exchange for actually killing him).
Ahhh the Jericho missile. A missile that implodes on itself, comes back, sprays peanuts everywhere and then implodes again.
It was a fairly new system, you wouldn't want to sell it off to the enemy until you had a good number of sales to your allies and the next amazing weapon was just about to come off the production line. They are running a business and the Jericho missile system would have cost millions to design and build so you would want to be get some return on that investment.