Conversations continued, images were designed and nobody answered if it was an extra cost (the image was designed before I replied again so even if I had asked again, which I admit I forgot to do, there would've been some work done before I could've stopped it). Now, this is probably where I am being stupid for thinking that since there was no mention of an extra cost when I asked I thought there wasn't going to be one. This isn't outrageous as I've bought from other etsy sellers before and requested custom orders at no extra cost, but I completely understand why they would add on an extra cost too.
However, because I asked, and it was never answered, I was a bit surprised when the cost was 150% of the original price, not including shipping to Canada which is another $10. It makes the cup more than $40 which is more than I wanted to spend on this random exchange (I was hoping for $30 or less) and now I'm stuck. Was I stupid for not pestering them about a response earlier? Was it bad_service that they never answered my question? I feel kind of stuck because they've done the work and it's not right not to pay them for that work but they also weren't upfront about whether it was going to cost more or how much more it may cost.
Do I have a leg to stand on to back out of the deal now that I've learned it's out of budget, or should I just suck it up and just not do business with them in the future? Or am I being a horrible customer? Sorry.
Also, to clarify, it was a graphical image that was made, the physical cup has not been printed (I understand that time=money too, I just know when I posted to bad_service (asking for advice) there was some confusion as to whether physical materials were involved or not.)