Streaky Bay has a singer of its own, and then the map goes quiet. The next two names are at Port Lincoln, several hours down the Eyre Peninsula, and after that the list is Adelaide: Hamley Bridge, Queenstown, Salisbury North, Woodville, Findon. That's the better part of a day's driving for anyone you book from the city.
Which means booking out here is a planning job, not a shopping job. The acts who do it are used to it, and a far west trip usually gets built around more than one night, a stay, or a run of towns along the highway. The supply within reach is mostly singers, guitarists, duos and a couple of DJs, and for a wedding on this coast a soloist or a duo is almost always the practical answer. Ask about the travel before you fall in love with anyone's set list.
Top picks are the nearby performers with the most visible reviews, then rating, then the closest; further afield the closest come first, and premium listings break remaining ties. Distances are straight-line from Streaky Bay. Ask each act whether they travel to your venue and what that costs.
Mostly by starting very early and being open about the distance. The local singer is the easy call, and beyond that you're asking someone to commit a weekend rather than an evening. Enquiring is free and books nothing, so send a few messages and see who is willing to travel.
Some will, for a wedding or a decent run of work, but it is close to a day on the road each way. Expect accommodation and fuel in the quote, and expect fewer replies than you would get in the city. If someone says yes, lock the date in writing quickly.
One person or two, with their own compact PA and a car rather than a van. Solo singers, acoustic duos and DJs handle this kind of distance without the costs multiplying. A full band on the far west coast is possible, but it is a project rather than a booking.
An act coming this far often wants two nights of work to make it worth doing. If a neighbouring town has something on the same weekend, say so, because it can bring your price down.
Coastal events on this side of the state get real wind, and it wrecks an outdoor sound setup faster than rain does. Tell the act if the ceremony is exposed so they bring the right kit.
The Port Lincoln acts on this list are still a long drive, but they're much closer than the city. Try them first and only widen the search if the answer is no.