Heya
$500 isn't enough for quality material I think. Especially if you don't already have the lights.
I would try to use the church environment as much as possible for your background and lighting situation.
A single flash can actually be enough if you bounce it off the ceiling or a wall. So you can choose a room and bounce a flash and take a look at the quality of the light and pick a good spot and need nothing other than what you already have. Then just do everything in that spot consistently and everything will match.
For your budget, buying lights:
Speedlights:
On a small budget, a handful of manual speedlites can do the job, I would just make sure to get some modern ones with built in wireless receivers. The Flashpoint R2 (Godox guts) system for example. $70 for a good manual flash with a built in wireless receiver. A single $40 R2 transmitter will control all the flashes and change their settings, etc.
For groups, you will want large modifiers, or simply bounce. I would just bounce in this case because the budget doesn't really allow for huge backdrops and massive modifiers other than umbrellas, and speedlites do not have enough spread at close range to a modifier to get big modifiers fully illuminated. So bouncing off a wall or ceiling at different points would be my suggestion with speedlites, without any modifiers. A bounce in front for key and fill. Bounce on a wall for side fill/hair. Maybe a back bounce to lift shadows or pop hair more. No need for a background. Just use the church, find an attractive spot to use.
Strobes:
You can also get wired strobes that are inexpensive. $50 actually can get you a very capable inexpensive budget strobe that has enough output and spread to fill a big modifier. Flashpoint Budget series for example actually are fine little strobes. 300ws is ideal as a budget strobe, but th 120~150ws are also totally fine. I actually use quite a few, and they've held up a long time. The benefit of strobes that are wired is no batteries, slave triggers (optical) to avoid needing transmitters, etc, so they can be tripped wirelessly as optical slaves, modeling lights are super helpful to see where shadows fall, etc. Strobes also have a lot of spread, so you can fill more area at closer range. Strobes can be used to bounce too, so you can do the same concept mentioned above, or you can get big 60" inexpensive umbrellas to use as bounce sources to cast light where you want and control direction.
What direction you go depends on budget, and how portable you want to be. Speedlites are very handy. But you have to keep up with lots of batteries. But, you can use them anywhere, no need for wires, lots of versatility and portability. Strobes can be excellent for a no-fuss, no batteries, just turn them on and start shooting setup for a studio. Also, inexpensive strobes can get you a lot of spread and output for the cost.
I use both. I love both.
I love speedlites for versatility.
I also keep some strobes inside for just turnign them on and shooting and not fooling with batteries and slow recycle time, etc.
Very best,