I've got a Cheap tip for you now.
The cost of magical ingedients has soared recently and the knock-on effect on the price of even the mildest of spells and curses is becoming noticeable. However, by following these few simple ideas for your own Lair-produced ingredients, you should be able to undercut any of the competing wizards in your area.
1. Grow your won Toadstools and Magic Mushrooms. Not only does this give you a free source of these key ingredients; it also makes very effective use of those dark, abandoned areas of your lair that you never go into. (Extra Cheap Tip: selective use of magic mushrooms can give a party a bit of 'fizz')
2. Build a roost in the grounds and you need never be short of Wing of Bat again.
3. Dig out a pond and stock it well. Voila! Eye of Newt whenever you need it. (Extra Cheap Tip: At the party described above, use frogs-legs to accompany the mushrooms.)
There, you're all set. Cheap Wizard, me. ;)