OK, money saving ideas (we don't have much money to spare for the garden):
Try growing most things from seeds, you can buy bumper packs (sometimes out of date) on internet auction sites, most of them, as long as they haven't been opened, will germinate.
Keep the plastic packs that mini-treats like biscuits and mini-cupcakes come in, put some seed compost in the bottom, sow the seeds, water & close the lid. Ideal mini-propagators that will fit on the windowsill.
Keep any polystyrene packaging and put it in the bottom of large containers. It makes the containers less heavy if you need to move them, and means you don't have to put as much compost in if you're buying it in.
Keep an eye on auction sites for cheap containers, don't buy full price ones, as lots of sellers will keep putting them on as auctions (instead of buy it now), decide on a price you're willing to pay and bid up to that. I have some great containers at a fraction of the price you'd normally pay. You may have to wait weeks before you get something at a price you can afford, so don't buy the plant before you've got the container.
School fairs and local bazaars and church sales are a great source of seedlings.
Empty mallows (marshmallow teacakes in some parts of the country) make brilliant containers for jiffy pellets, just put the pellet in the hole, add warm water, pop in the seeds, and find a 'lid' from clear plastic containers that fits, and you've another windowsill propagator.
Keep packaging that's fairly robust for plant trays. I find clear ones from prawn toasts make excellent propagator tops and they're strong enough to use as plant drip trays.
Yoghurt pots make great plant pots for seedlings.
Make bigger plant pots and planters from the tubs that stain remover comes in. I've got bright green ones and bright pink ones in my garden!
Don't buy seeds for things like peppers and squashes. I've grown most of mine this year from seeds from fruits brought in supermarkets (this won't work with tomatoes because of the coating they have, they have evolved to need to go through a host (human or bird) to remove this and be spread away from the original plant!
Buy more items than you need (a lot of plant mail order places have offers on where the more you buy, the cheaper the item is). Club together with others to get the best offers, and that way you won't need to pay postage.
If you have tesco clubcard vouchers, don't pay for your shopping with them! I've just ordered 3 climbing plants with a £5 clubcard voucher. The offers change every couple of months, so keep checking to see if they have anything you need.
The 'cheap supermarkets', and you know which ones they are! Have some great offers with plants and equipment, you may need to be there at the start of the day to get what you want.
Don't buy specialist 'garden' stuff. Lots of things can be subsituted for things that don't cost as much, so substitute horticultural grit for sharp sand from a builder's merchant. You can put this around plants to stop the slugs, around bulbs to stop them from being eaten, and as a soil improver into heavy clay soil for drainage.
Baby food jars or potted meat jars make great twine holders if you drill a small hole in the top. This keeps your string clean and dry and tangle free.
