545rfe filter and trans fluid
That's a good price for a Wix, I would think that the mark-up at a parts store would be 50% more. Wix would be my go to filter.
The $35 for fluid is about as low as you'll get in a quality oil. However you didn't mention which brand you're considering.
I have a 46RE in my magnum swap and uses the same oil. I found some Valvoline ATF +4 at my local Walmart for $6.99 a quart, whereas the same brand at the parts house was selling for $9.50 a quart.
So if you can source your filter and fluid in one place at them prices I would do it.
Don't monkey around with the off brands, you may end up doing it twice due to poor quality control standards.
Yes, $100 is a pinch especially now, but its well worth it.