Stilltime17 I will second or third what everyone is saying about the local dahlia society in person tuber sales!
Local to me connell’s dahlias have a lot of tubers priced wayyyy cheaper vs anywhere else I have found online. For example variety “parkland rave” is 6$ at connells and 10$ or above everywhere else. They are going to do another restock of online varieties at some time. https://connells-dahlias.com/
Swan island Dahlias I have bought from in the past. They are a bit more expensive vs other places but I have had every one of their tubers grow for me. Their website also has great search filters, reviews and descriptions of different varieties.
Another thing I would suggest is growing some varieties that are known to be productive/vigorous. For me (someone very new to growing dahlias) I appreciated and enjoyed the ones that made lots of flowers and thrived in less than ideal conditions. I wish I would have avoiding falling for the hype of some of the “trendy” (and expensive !) dahlias. While they may be trendy or cool the 3 flowers I got off of them didn’t bring me nearly as much joy as the 20 flowers I got to pick from Ivanetti 😂. Ivanetti still is a beautiful flower it just isn’t hyped up, sold out in seconds online and “trending” right now. But Ivanetti will grow loads of blooms even with semi shade and constant slug and aphid attacks 😂(In my experience).
