To settle my own curiosity, I broke down the costs for my most recent amp build. I thought others might be interested in the results. This is a ~15W single ended build. So, the most expensive components are still cheaper than building a DIY 50/100W. The only area where I really could have saved any money would have been building the headshell myself. At the time, I didn't have a dovetail jig.
I can save you a little time. dont order from weber, amp kits that is, Ordered blackface dekuxe with a head, not combo cab, What do think arrived after several confirmation orders. Luckily my customer said it s cool I was thinking about a combo anyways.
I've never ordered an amp kit from Weber (or an entire amp kit, period!) but I have ordered miscellaneous parts from them. They have messed up about 30% of my orders. It's never been anything major and after a phone call they have always made it right. But... yeah. I can't whole-heartedly recommend them either.
I feel certain they do. Mouser plainly lists the price breaks on their website. Matt at Musical Power Supplies lists price breaks on volume on his website as well. I'm sure Heyboer would as well if you're ordering direct.