I remember some folks on Fleabay who sold the HDD already prepped that a great many people used some years ago who were less expensive than WeaKnees. I understand your looking for an alternative to WeaKnees because even their less expensive service to send you a fully prepped HDD that you install is a really big mark-up to the cost of the HDD itself (considering not much labor involved and they do this prepping stuff all the time in a highly efficient manner), and we now how
INexpesive (but very good quality) the HDD's they use are. WeaKnees used to have a service option (do they still offer it?) where you send in YOUR fresh HDD, and they prep it for you and ship it back. I could not find that option the last time I visited their site. However, I ended up getting a drive from WeaKnees for my S4 unit anyway for two reasons:
1. Absolutely pressed for time and really tired with a few health issues and getting on the PC was taking time for very important personal matters and it was a few MONTHS before I realized--yet again--that I was NOT going to get around to preppin a drive, and household members were on me to get it done, so it was WeaKnees to the rescue. I can do the Roamio switchouts in very little time because no need to power up the PC and prep needed up to a 3TB HDD (large enough for me), but even then it took me over a month to get around to it.
2. WeaKnees is reputable and if there is a problem, we know where they are, and they do work to satisfy you, and they do offer a warranty for their products and services. They do return emails and answer phone calls

, and they do GOOD work.
The best of luck no matter what you decide to do.