I am lucky enough to work in an estate where oak trees are regularly maintained and so I get hold of a regular supply of logs free of charge. For the other woods it depends on the quantity you need. For smaller quantities you can buy online from people James at Smokewood Shack but you will probably be able to buy a quantity of a common wood like apple or oak more cost effectively (usually by the trailer load) from a local wood fuel supplier.
The charcoal briquettes I buy online as they are not usually available through local stores. The important thing is to get good quality briquettes that produce no smell when they burn and burn long and slow. My briquette of choice are the Heat Beads which give a very long heat profile or the Weber Premium Briquettes. I also like the Big K restaurant quality briquettes (not the ones from the supermarkets) but these need to be broken into smaller pieces before use in a Kettle BBQ. The quality briquettes may appear to cost more up front but as you use so much less of them they actually work out cheaper overall. 1.5 Kg of Heat Beads can give up to 8 hours cooking time.
The Heat Beads or Weber Premium I usually buy from Wow BBQ and if you buy 5 or 6 bags the next day delivery is free
For the BigK you should bee looking for this type and not the supermarket bags.