Hey there,
I don't charge for applications. I have had good luck recently listing on Zillow, which does charge for applications, but I think allows tenants to apply to multiple units for the same fee. As a result, you willa get some applications.
When I use Zillow, I do not allow people to apply without reaching out to me first. You can ask them a couple of questions like "when are you looking to move?" and or "minimum credit is 650 and income to rent ratio is 3" if you think this sounds like you, let me know and I'll forward you a link to apply. The reason I recommend this is that it is so easy to apply with a push of a button and you don't want to waste your time.
With 150 potential applicants, your price point may be a bit low. My recent rental had about 40 people reaching out with about 10 applicants. Even that amount was labor intensive.
With COVID, I would limit viewings to people who have applied and are pre-screened to qualify. You don't need 150 showing up. If you do 5-6 showings an hour, you can show it to 20-24 people, and should find a suitable tenant.
Good luck!