I certainly wouldn't use an easy out if at all possible. These studs are usually steel, and they are in an aluminum head.
Are you turning these the correct way? (leave no stone unturned)
Using an impact driver?
Jerking on these nuts? (not meant to sound the way it does)
If you proceed to go any further, soak the rest in PB blast. Spray on every 4 hours the rest of the day for about 3 to 4 applications and let sit overnight before doing any more. Use a long breaker bar, as long as you can get on and use, or a pipe as an extension on a ratchet, to apply high torque with gentle effort, turning counter clockwise (just in case).
I have found turning some bolts too fast will lead to snapping, impacts the same, while using a long handled breaker bar, and a very slow even twist will not.
As for pulling out the 2 that are already broke, again, the PB blast soak, heat and GOOD vice grips should work. (cheaper quality may slip and twist easier) Maybe have a pipe that will fit over the adjusting nut side of the handle to give that extra slow twist high torque, an needle nose variety may be better suited, but may not be, considering.
As for expense of someone else doing it, expensive is relative. That depends on what you consider expensive.
Cost is localized. How much people are going to charger per hour is going to be different in your area than another persons.
How much time it could take depends on if the rest come out easy as they should or continue to do what they are doing.
Who you take it to is a matter to be considered. A shop or person that specializes in bikes will probably give you best results, but may charge more. Any decent auto mechanic could probably it, may or may not charge less and may or may not give you the same results. Your uncles best friend who works on their car could probably do it, probably for less, results may vary.
Time to get to doing it can vary too, depending on their current workloads.
I just looked at where you are from, if you don't have PB blast there, find something equivalent. Apologies.
