The least expensive route to becoming an RN is going to be getting your ADN from your local community college. As others have already noted, there is an overwhelming preference for BSN's and depending on your location, you may face considerable difficultly in getting a nursing job. That said, getting your ADN, passing the NCLEX and then going on to get your BSN from a state institution is definitely worth considering and will almost certainly be the lowest cost route.
I speak from experience in this, having done precisely that for my BSN. In my case, it was the evening/weekend nursing program at community college, which not only was relatively inexpensive (tuition and fees for the program ran about $6,500, though this was some years back), but also allowed me to continue to work full-time. (An aside: working full-time and completing a nursing program requires commitment, planning and a supportive spouse - it is not for the faint of heart.) Once I passed the nursing boards, I applied to the RN-BSN program at a state university. Not only was the tuition reasonable (about $8,000) but the program was offered via both a traditional classroom or on-line. The total cost, including books, fees, equipment, etc to get a BSN was less than $17,000.
Like you, I was a second-degree student when I enrolled in the ADN program, and so had a significant amount of the required coursework out of the way. I'd be surprised then if the total cost for the ADN-RN-BSN wasn't something like 40% less the $35,000 you cite. Your cost is likely to be significantly greater going the ADN-RN-MSN route, but if you can find a state school masters program, may not exceed the $35k figure. Just a guess on my part though.