Man - I keep getting to the mid 40s and then my weapon is just too weak to kill that many, as well as money being just... gone.
My biggest frustration is 9/10 times there is JUNK in the shop. The one time you find something you want, you are broke. Also I am in day 40 and I get lvl 1 weapons dropped?
I have had a lot of fun. Weird though - ~day 40 the waves had more attackers - but were much much less powerful.
I am going to start over and TRY to not carry over. Looks like you can't get simple medals like the Chicken ones. It can be dang hard though - that is why I started to Carry over.
FWIW - Gravity gun with 2 leech mods makes you fantastically secure.