Anything that had a different design in one area versus another is considered CUSTOM quilting. Doing meandering just on the borders would be custom. On top of that, you'd want to ask the LA'er:
1) Would she accept a quilt that was already partially quilted (assuming you are going to SID or otherwise straight line quilt the pineapples -- they need something to secure them or the quilt will come apart over time with laundering and/or batting will shift and bunch)?
2) Is there a minimum charge for her to do work?
3) What do you need to do to prep your quilt for LA'ing?
4) How long would it take to complete the job?
5) And, of course, make sure you get everything in writing: type/color/weight/brand of thread, description/sketch of design, cost, delivery date, what happens in case of a cost overrun, type of batting & whether you're providing batting or LA'er is, whether binding is going to be made/attached at all, and if so, how?
Cost varies by geographic area. By me (Chicago suburbs), custom quilting typically runs $0.05 - 0.06 per square inch (take length x width of your runner and then multiply it by 0.05). So a 20x50" runner would be around $50. The LA'ers by me have a minimum charge of $45 so I'd probably just have them do the straight line (SID) quilting & something in the borders -- why not pick a really lovely design if you're paying for it to be professionally quilted -- since it's going to end up somewhere around the minimum charge anyways?
FYI ... members can get kicked off the site for promoting their quilting services in threads (other than a link to their website in their signature). Your best bet is to get recommendations from those who have used their services here & can provide you a link to their business, allowing you to contact them directly rather than through QB. We have, sadly, lost some really incredible members this way in the past so it's best to just conduct any business off-site, imho. That said, although I quilt all my own quilts, I know I've seen some really incredible professional quilters here on QB!!!