I do them mobile and just buy a big individual lash glue from suppliers. I'd say charge £15 to make it worth your while with travelling etc. takes around 15 mins average.
I have never had a mobile client ask for removal they either let them come off gradually or get more put in before they'll come off. I always advise to be gentle when removing make up etc to avoid unnecessary pulling eyelashes out.
I always offer removal service bur have only had clients in salon take me up on that. The beauty of cluster lashes is they are so temporary and low maintenance for the client that they can manage them without any commitment.
I juse use salon system lash adhesive black and their lashes, they do knot free. I charge £10 full set £5 flicks as part of a make up service, ive never been asked for removal but you should always stock remover just in case.