I run (road, hills, trails) but I also cycle, MTB, swim, climb, do a bit of hill walking, kayaking, go to the gym - weights, HIIT... there's a myriad of things out there. You don't need to be inactive in between runs. Mix it up. It also helps stop the boredom.
You won't get a waterproof shoe... If you are running through trails which are muddy etc water will inevitably get in over the top of the shoe. Therefore if you have a waterproof shoe the water will sit in your shoe, sloshing around and it will not escape. The water needs to be able to get in so that it can also get out. Trail and more so fell shoes are generally very light, minimal but far far grippier soles. They are not designed to keep your feet dry but to be light so that when you also pick up mud etc you are not dragging a heavy shoe into the bargain. They are designed to have little support so that your feet and ankles move with the changing terrain, you build stronger ankles into the bargain.
I do also have a pair of Asics which are a kind of hybrid shoe as they are a bit more cushioned like a road shoe but with a bit more grip/tread. Maybe you need something such as this. I have never worn NB but I would almost always recommend Inov-8 (currently running hills in XT-Talons). If you are running mostly off road and are using them for off road races, I'd stick with what the main purpose for the shoe is. (i.e. you want them for an off road race). Price wise I have never seen much under about £70 but ebay/gumtree would I think likely have selections at reduced prices.
TallGirl, I was thinking of Mallorca as my 1st IM next year as it is a late season race but my issue is it is a sea swim. I am far more comfortable in a loch (lake).. but not sure what options there are? I am probably aiming for around the same timescale as you!!
Runners will tend to just buy what they need as and when (as do most sports people). Having random stuff every month or even less is either going to result in you having a load of stuff you don't use or too much stuff of the stuff you do use... therefore loads of stuff not getting used. What kind of things were you thinking of? How were the pricing categories of these boxes going to work and the frequencies of them? A new pair of runners every 6 months might work but then..... I'd probably just buy a pair I can try on and buy myself. Anything smaller.. yeah I'd still just buy it myself and if it's an edible product, trying out things for yourself is the best strategy. If it's not a random selection of gifts and you pick the combinations then wouldn't you be better just buying the individual gifts? I don't know how this would work???? If it's regular purchases of things you need, there are plenty of in store and online retailers already catering for these sorts of things and I would say it's unlikely you'd be able to make any money on this. If it is race specific gifts i.e. marathon gift box for example as asitis said, it is a before and after the event thing rather than every week/month. The plan is managed as you go through it and deal with all your problems/issues in training and what you need at the time. Sorry, I don't think this will work as a business.
Also find Camelbaks more comfortable than a belt which I just find bounce around too much with all the weight around one area. That said I don't take anything for anything up to Half distance... although if it was a hill/mountain run I'd probably take something for over 10 miles... Also only take water in bladder pack. If I felt I needed it, would throw some jelly babies in the front pouch.