You really can't say many bad things about mulch. It's amazing stuff - a layer of something that you put over the soil to keep the moisture in, which means you don't need to water your garden as often and your plants won't be as stressed.
If the mulch is thick enough (4 inches/10cm) mulch will keep weeds down, and save you work. If it's made out of something biodegradable, it'll break down and add nutrients to the soil. Most mulches other than pebbles and stones are biodegradable, one of the best mulches being pea straw.
Mulch can be very cheap if you buy it in bulk from a hardware store or landscaping outlet and can get it home yourself in a trailer. Delivery can get expensive even if you are right in their delivery area.
Possibly the cheapest - but not the prettiest - way to mulch your vegetable patch is to collect all the useless mail you get and shred it, with a household shredder that costs around $20-50. You can either put the paper shreddings on the surface of the soil, dig them into the soil a little or add them to your compost heap. You'll need to add nitrogen, but in the long run you'll be saving money on watering, time on weeding and of course saving a little bit of space in landfill.