The left is indeed the better deal. Just use the area of a circle (pi*radius2) divided by either six for the left slice (since 60 degrees goes into 360 degrees six times) and eight for the right (45 into 360 is . That gives you 18.84 square inches for the left and 19.24 square inches for the right. Divide by the price for each (that is 1.5 for the left and 1.7 for the right) and you end up with 12.56 square inches per dollar on the left and 11.36 square inches per dollar on the right, making the left slice slightly better value for money.
I went another way of finding it out. There's 6 pi square inches on the left, and 6 and 1/8 pi square inches on the right. Put another way...
Left: 48/8 pi square inches and Right: 49/8 pi square inches
Therefore the ratio of left to right is 48 to 49, and you can multiply 1.70 (or 170 cents) by 48, and divide by 49 to get what it's price would be if it were trimmed to be the same area as the left slice. Multiplying by 48 is trivial enough because you can just multiply by 50 and subtract 340 from that. Dividing by 49 isn't quite as simple. Regardless, it's possible to get with some simple long division.
Once you do the math this way, you get approximately $1.53 for the right slice, making it a bit worse.