I've just gotten a 172 +7 set. It took a LOT of grinding. I made the whole set out of +4 pieces. How it's made:
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+4 head
+4 head } +5 head (costs 6,500,000)
+4 head
+5 head
+5 head } +6 head (costs 6,500,000)
+5 head
+5 head
+5 head } +6 head (costs 6,500,000)
+5 head
+5 head
+5 head } +6 head (costs 6,500,000)
+5 head
+6 head
+6 head } +7 head (costs 6,500,000)
+6 head
Total cost of +7 head ((Price of Combination coupon only) 97,500,000)
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+4 body
+4 body } +5 body (costs 6,500,000)
+4 body
+5 body
+5 body } +6 body (costs 6,500,000)
+5 body
+5 body
+5 body } +6 body (costs 6,500,000)
+5 body
+5 body
+5 body } +6 body (costs 6,500,000)
+5 body
+5 body
+5 body } +6 body (costs 6,500,000)
+5 body
+6 body
+6 body } +7 body (costs 6,500,000)
+6 body
Not enough time to do the arms also, but the total cost (the combination only) was 292,500,000 gigas.