You can fix this problem yourself for a LOT less than $300. However, I just want to note that there are different types of caulks for roofs (eg, EPDM/rubber) and general caulking. (you labeled this thread as "best roof caulk" and then asked "what's the best type of caulk to use" for a specific repair issue not directly related to the roof) The answer is it all depends.
For EPDM/rubber roofs, it's recommended that you use a self-leveling type of caulk such as those made by Dyco (C-10 Flow Seal), Dicor, or Alpha Systems. Always double-check or confirm that your caulk will be the proper type for any given surface (eg, rubber roof surface on a TT).
For general caulking such as seams, windows and the like, I would not recommend the use a silicone based caulk because, as correctly stated by another post on rvforum, the problem with silicone caulk is that once it is on, nothing else will stick to it. You can't re-caulk or even touch up your work without removing all the old caulk and cleaning thoroughly with mineral spirits or other solvent. Also, silicone based caulk will shrink and pull away from the adjoining surface over time. Upshot: Much better to use a non-silicone type.
For some reviews on caulks, see these links:
Although you havenít specifically identified the problem, Iím going to assume that the problem is due to the movement of the awning support bolt that is screwed into the side of the roof panel. In other words, when the awning was adjusted, either a new bolt hole was drilled and the old hole was not properly sealed (case #1), or, the old bolt was loosened but not re-caulked upon tightening (case #2). In either case, you have water leaking down the inside portion of your wall.
I would recommend the Geocel Proflex caulk (aka as just "Proflex"). It is advertised as "Pro Flex RVô Flexible Sealant - Withstands joint movement and temperature change due to RV travel. Stays elastic and is paintable. Adheres to damp, frozen, and oily surfaces. Not recommended for EPDM or TPO applications." One thing to know, however, is that this stuff is very sticky and can create a mess if you're not careful.
For case #1, inject Proflex into the hole. Since you probably wonít be moving your awning bracket, be careful to only get the caulk in the hole Ė do not get caulk in the gutter area which will block the flow of water and allow the water to seep up to the bolt threads. Use your finger to make a smooth exterior surface. Allow the caulk to dry.
For case #2, back-out the bolt. Inject Proflex into the hole; apply some Proflex to the threads of the bolt; tighten-up the bolt. Allow the caulk to dry.
You can do this yourself; good luck.