Just swap out the crank arms. Keep the same rings, spider, and BB. Get your LBS to locate you some Shimano 165mm crank arms. That's your cheapest option. You're not going to get any rebates at the shop from a crankset with 1000mi, and selling a 105 crankset isn't going to get you much.
Thanks for the input! I was uncertain whether only changing the crank arms was an option They are difficult to find online
I always feel better knowing what I want before I go in so I don't feel like they are trying to sell me something I don't need