This is the cheapest welcome mat I could find, it was in Ikea for less than £1 and I saw this and thought I could do that (but a bit geekier of course).
I didn't use spray paint for mine as we only had silver and I do not spend money on this kinda stuff! So I used blackboard paint (only non water soluble paint I had in the house) and gave the letters a coat of PVA after (I <3 PVA).
Here are some more pictures, just cos I am a generous and sharing kind of person.
With the stencil on
I'm pretty happy with how it turned out, if it gets wrecked I am sure I can get another ultra cheap mat and do it again.