Costs for a LBS to supply and fit sound good to very good, especially for the chainrings, dependant on spec of parts, we don't know what type of bike or the spec of the parts to confirm this.

The chainring bolts, are part of the chainset, they are the bolts which hold the chainrings on, so you already have them, and they can be re-used.

For your issue, have you checked where the cable from the front mech is going, as this can cause the type of noise you are hearing, if it hitting the frame on every revolution, when the bike is stationary, this will probably not be seen as causing the issue.

Not sure that changing any of the drive train will actually fix the clicking clicking problem, could also be the bottom bracket, no-one has mentioned that yet.

For your chain being worn, would suggest that it is worth getting this replaced, as if worn, it will wear the cassette / block, then the jockey wheels and chainrings, again, knowing your bikes spec woudl be useful in knowing what you have, and approx cost.