I have moved your post to the Excelsior forum to encourage feedback.
Cost information is on Excelsior's website here: Excelsior College Costs & Financing for Nurses - Excelsior College - excelsior.edu
You pay an annual fee ($495) if you do competency exams (testing out) rather than doing the required number of full online courses per year (I think the threshold is 12 credits per year to waive the annual fee). It is much faster and less expensive to do the exam option (see the cost link above). The three ways to complete the nursing theory requirements are the exam, the course, and what they call a "nursing conference" which is the exam plus some guided study; the cost for that is somewhere between a plain exam and a course. The three options are discussed here: Nursing Theory Completion Options - Excelsior College - excelsior.edu
How long this takes is up to you, there really isn't a formula to calculate how long it will take. Most students seem to take about 2-3 years if they don't put it on pause too much. Be aware that the current wait time for the Clinical Performance in Nursing Examination (CPNE), the clinical capstone exam, is about 12-14 months right now, so you have to factor that in as well.
I believe the college is transitioning from Blackboard to Canvas for its online courses, but I haven't been a student there for a while so I am not sure. But like most online course software, it just takes a little getting used to.
I hope some of that was helpful! Feel free to ask for clarification, or if you have other questions. There are quite a few students and grads around.