Buying from resellers come with risks, you are likely buying from a shared pool with other white label resellers. These proxies are often times labelled with high fraud scores with low speeds as they are being utilized by multiple sources as exit nodes. I've been in the business long enough to realize this and thats when I build my own network. Invest some money and time and do it the proper way.
There is a site I know of called spur (not affiliated) they buy their data from transit providers (ie LUMEN) and other large ISP to identify residential proxy traffic. You can try for yourself and see how many providers are sharing the same residential IP's all likely resellers.