No answers yet, so here are a few ideas.
Before buying anything - You need a system with "procedures" for cleaning, maintenance etc which suits you and your schedules (working, children etc) and with that will come the type of preventive strategies which suit your needs. A lot will also depend on access to water and electricity.
Concentrate on prevention. Metal food bins are expensive but earn their keep as they are rodent and chook proof. DE treatment works well to prevent mites. Do you need an electric fence (etc)? People worry about foxes, but I've had much more trouble with domestic dogs. do a bit of risk analysis.
Don't buy lots of material with a limited shelf life. Most things are easily bought when you need them and storage creates problems in itself.
Things like anti-pecking spray you might never need so just find out where your nearest farm supplies shop is located and get it if you need it.
Many household first aid items are just fine for chooks, although once used for them II'd keep them just for chooks. Savlon liquid and cream, dettol, wound powder, vaseline, scissors are all things you'd find in your first aid/bathroom cabinet.
Lots of posts on sanitizers - but again bleach is OK (check for plastics); just use the same precautions as with children.
You will need to worm - I do it every 6 months using flubenvet. Again don't buy until you need it as it has a shelf life. Vaseline or vegetable oil for scaly leg seems effective (again see posts)
Wood chippings are fine.
Diatomaceous earth (again see posts) is best ordered via ebay and get a big bag much cheaper than poultry suppliers and it will keep.
I can't comment on "I like chickens", but apart from the DE (which i would not get from them) you might find the local farm supplies shop best (e.g. for Flubenvet) because, although they may be a tiny bit more expensive there is no delivery charge and you'll be going there anyway for your pellets.
Most important - don't panic. It is easy to read this forum and think only of problems, but that is what it is for; it doesn't reflect everyday experiences. Enjoy the chooks.