Usually I would recommend checking awardhacker.com for the miles needed. However, the listing there isn’t exhaustive, showing me mostly Oneworld redemptions on the route to Islamabad.
If you want to buy miles for your purpose: Generally it should work out. However, please keep the following points in mind:
- Availability for award flights usually differs from paid flights, e.g. awards are only allowed for certain booking classes
- Avianca (owner of LifeMiles) is bankrupt. I personally don’t think, that sending 2.000$ to this airline is a good idea in this situation
- You would not only pay 180.000 miles for your business ticket, but also have to pay taxes + fees for an award ticket. I don’t know how much Turkish Airlines charges, but you can expect at least €100 + €200 per person, maybe a lot more.
I just checked the options with Miles&More (which are „Lufthansa Miles“), but Business Class is 112.000 miles + 440€ per person roundtrip.
Another option might be a ticket from Heathrow, as Virgin just put up a sale from LHR to ISB. You could grab Economy Tickets for €400 p.p. (roundtrip), Premium Economy for €660 or Business for €1.100. However you’d have to depart from London then. You can find these options in Google Flights.