just me?

I would just say no.

Also, since when 5K's are considered 'distance running'? :laugh:

I would imagine for someone who isn't a runner, that would be distance running, no?

Derail it when you say .. "Sure, no problem. All those services are going to run you around $7500. I'll take a 50% deposit and we can get started"

someone is taking advantage of you!

I'd say SCREW IT

I would just have them google the "Couch to 5k" plan, simple, easy to follow, & you're off the hook! (+ it's FREE!!!)

This... And then if you haven't got time for the rest then you say so. Learning to day no is tough, but it gets easier over time and eventually my hope is that people will stop trying to take advantage.

If your always the nice 'yes' girl or guy, then that's what's you'll always be used as. Only you can change that around! Good luck!

^ so true, saying no takes practice, but after the first few times you'll be astounded at how empowering it is!!! spoken as a previous pleaser/doormat!! what are you scared of, if she squawks a bit so what, if you're scared of her slagging you off and she threatens it tell her you'll see her in court

Say no. You have to set the boundaries here

Personally, I would draw up an invoice for ALL the time and expenses required (training, gas, hotel and my entry fee for the 5k), add 10-20% and send it to her with a note saying "I am happy and excited to do this for you, here are my costs and I'll be needing them paid up front/by Wednesday night - then I can get started on designing those t-shirts, send out that email with the training schedule and get training y'all on Sat & Weds".

Then she'll either pony up or stop hassling you.
Asking people (nicely) to put their hand in their pocket when they are pushing a favour gets ride of the p*sstakers pretty quick.

No good deed shall go unpunished...

Maybe you need to set some boundaries/rules on what you are/aren't willing to do for this! Or, just back out completely. I dunno... unless maybe you can work some of these folks into your client base.

Sounds to me, what with all the "she should be paying you" replies, that you have a business opportunity here.
I concur with sitting her down and having a conversation as nicely as possible about how this snowballed from what you initially agreed to and now you are realizing that the amount of support they need and the time it takes to create 10+ plans is cutting into your workday and impacting your time with clients who are paying.
If you want to keep participating with the group and do the race, take the C25k suggestion and pass that along for anyone on your team who wants to follow that plan, But, also offer to continue to help with support and custom recommendations at your normal training rates for anyone who wants to become a client for your personal help.

A possible response would be that she thought you were doing this with her as a friend. Maybe a little shock and upset that what you were first doing for free is now something you'd like to be paid for. If so, acknowledge this, empathise that you understand the viewpoint considering you are changing the arrangement they were expecting Then refer back to the amount of time involved with how this has worked out and that taking on this commitment completely for free is expensive for you as it's taking X hours a day/week. If you explain that this has become the workload of a small business she will hopefully see your point and understand.

If some of them decide to pay you then you have the starts of another aspect of your training services. You could become known in your area for race preparation training. This group might very well return to you for the next races to do this again if it goes well.