So here's the dilemma:

I have been assigned to work at a remote location. Following are my options:

1 - Hilton (Hampton Inn) - approx 170 / night
1 - Marriott - Townplace - approx 210 / night
1 - La Quinta

Even though the Marriott is $210 / night. The point stay is 50,000 for 5 nights (1 night free) - category 2. Most of my stays are 5 nights:

So,
I could stay at Hilton
- spend $170 x 5 plus another 18% (taxes and fees) = $1003 / week
- earn 170 x 5 x 44 (Diamond / credit card / promotion) = 37,400 points per week

I could stay at Marriott
- use 50,000 points / stay until I run out of points.
or
- $210 x 5 plus another 18% (taxes and fees) = 1239
- earn approx 30,000 bonvoy points

in terms of value even though the 50,000 points are for the $210 / night hotel, I compare it with the other option at $170.

So 50,000 points to avoid $1000 spend. so 2 cents / point.

Question: where and how do i buy more Marriott points.

Waiting for a promotion where the bonus to buy is 100% or so. I understand I am limited at 80,000 / yr so a total of $160,000.

Convert Amex Membership rewards into Marriott ?
Convert Southwest points into Marriott ?
Convert chase rewards points into Marriott ?