You don't need to worry about testing facilities for CLEP, DSST or ECE exams. The test centers are authorized by their respective institutions, so they are all safe. I would highly recommend finding an Internet-Based Testing center for any DSST exams, but that's really a matter of personal preference -- some people like the paper-based exams because there is no time limit.
I cribbed the bulk of my plan from Lawrie Miller's bain4weeks.com site. If I were starting over, I would not follow exactly the same plan, as I ended up taking more ECE exams than I needed to. ECE is significantly more expensive than CLEP or DSST, and while their testing procedures are very professional and entirely fair, I found them a little more stressful than the CLEP and DSST exams. I highly recommend reading everything on that bain4weeks.com site, though. The site is somewhat out-of-date now, but his study recommendations are still right on, and the recommendations of which exams complement one another are very good as well.
As far as budget goes, the number in my head has been $10,000. I have not been nearly as rigorous as I should be about keeping track of my expenses, but I am quite confident that my total will come in under that figure -- including books, IC, sample exams, VangoNotes, etc.
I do recommend choosing a school and enrolling early. My feeling is that these schools are wonderfully inexpensive already, and I don't need to nickel-and-dime them beyond that. I chose Excelsior, and nothing I have heard or read since has made me regret my choice. Everyone there has been very helpful and cooperative, and their online course materials are very good. I believe TESC has some advantages for certain degree programs (such as MIS) and for using FEMA credits (I didn't use any).
One more thing you should consider is the GRE subject exam program. If you decide to enroll at Excelsior, you can earn as many as 30 credits by passing a GRE with a high enough score. That comes out to less than four and a half dollars per credit -- can't beat that deal with a stick!
But the GREs are only offered three times a year -- the next seating is April 12, and you would have to register by March 7.
Good luck!
-Gary-