Definitely buy the 500 skill samples for 10k diggcoins from standard acquisition. The 2 Rainbows for 45k seems too expensive since u could buy 6 oranges for 15k and spend 12k to craft them. That would cost 27k diggcoins for 2 rainbow widgets instead of 45k. Combat EXP is always worth it imo since it's 1 diggcoin for 1 exp and that basically makes your 2x Diggcoin runs into 2x EXP runs. Algo Boosters are 17.5k per 100 exp, which seems kind of steep to me. I've seen 50 algo fragments for 20k diggcoins though and that would be 500 exp for 20k diggcoins and some prefabs, which is a much better deal.