I agree that it's hard to estimate without knowing more, but I'm guessing that you are going to be getting into new headers to move the support and I'd guess you'd end up in the low thousands. Are you also going to need match masonry? That'll add to the cost, too.

I strongly disagree. I studied structural design for longer than most engineers and have been practicing architecture for 50 years but I would never modify a lateral bracing system for roof trusses without the help of a structural engineer even if I had the original structural drawings and calculations. In too many cases I have learned from an engineer that the original design was inadequate to the point of being dangerous. I just finished a project where the owner did not want to pay for an engineer but when I told him I would have to resign he agreed to hire one and was shocked when he learned that the structure of the building had never met the building code or acceptable engineering practice. I had to explain to him that a structure was not "grandfathered" since it did not meet the building code when it was built. His contractor was very capable and thought he could modify the structure himself. the structural reinforcement he had already done had to be replaced. He thanked me later for intervening. Advising people to rely on contractors with little or no structural training could cause them serious harm.

Your picture seems to show 2x4s, a doubled sill plate, a gap, then a header. If that header spans from an exterior wall to an exterior wall, the 2x4s and doubled sill plate aren't doing any work other than holding up drywall.

I’m sure if you have the room (at least 5’ for a small slider) you should be able to have one installed, and it sounds like a good solution for you. Since that appears to be an exterior door I would assume that’s a load bearing wall but a good installer should know how to handle that.