Rome. Villa Borghese October 27 or 28 tickets

Johnnie, did you mean Villa Borghese (the park) or Galleria Borghese (the museum)?

If you meant the museum, did you try the official ticket office first?
https://www.tosc.it/en/artist/galleria-borghese/
(Ah, I just looked and tickets are not yet for sale for your dates. Check back later.)

$75 per person or per a group?

Villa Borghese the museum

I did try the official website. They don't show tickets available that far in advance yet.

So check back in a week or so.
The info for their guided tours is on this page, of you've not see it yet.

https://galleriaborghese.cultura.gov.it/en/visita/visite-guidate/
"The Galleria Borghese provides guided tours in Italian and English conducted by qualified staff from the company Gebart. Reservations are required and permitted subject to availability. Each guided tour if for maximum 15 people.

The cost of the guided tours is €8, plus ticket price and reservation fees.
Guided tours on the permanent collection, lasting 90 minutes, take place on the following days and times:

· in English from Tuesday to Sunday, at 9.10 a.m., 11.10 a.m., 3.10 p.m. and 5.10 p.m.
For reservations kindly contact +39 06 32810 or click on BUY"

ok thanks. is the $75 for a guided tour in English?

You are very helpful! Thank you. Would you know if this tour would be better than one from a tour company? Possibly Viatour etc.
?

Also, I need 4 tickets. Do I have to buy them separately? or can I enter 4 and get all tickets at the same time?

Happy to be helpful! :O)
Not sure where you're seeing $75. Clicking on an available ticket on a random date, it costs € 20.00 (including reservation fee) for an adult ticket if purchased through https://www.tosc.it/ The info about tours from the museum's websites states that it's an additional €8 per person for a tour.

Yes, you can order all 4 tickets at once if there are 4 of the same time slots open.

No, I would not purchase through a 3rd party like Viator (which is not a tour company but a clearing house for tour companies.) Here is some feedback on the museum's tour from a previous poster:
https://community.ricksteves.com/travel-forum/italy/recommendations-for-guided-tour-of-the-borghese-gallery

If interested in booking through an independent company, here are a couple of tour companies which are frequently recommended on the forums for various locations in Italy:

https://theromanguy.com/tours/italy/borghese-gallery
https://livtours.com/tours/baroque-masterpieces-borghese-gallery-tour-semi-private/
(That one will cost more than you're budgeting)

Context and Through Eternity are good too but both will cost you even more than the two linked above.

Thanks so much!!!!

Crossing fingers that you'll get those tickets (they can sell out quickly when they become available)! The museum is wonderful, and we enjoyed it much more than the Vatican's.