I'm new to home brewing. I have brewed a couple Mr. Beer kits and most recently two extract kits from Northern Brewing. I love the simplicity of a kit, but I'm ready to branch out. I don't have the equipment for all grain yet so will stick to extract brewing. Will I save a bunch of money if I buy separate malt extract, specialty grains, hops, and yeast vs buying the kits?
There are savings to be had by shopping wisely; however ... they don't exactly add up top a bunch of money for relatively small batch sizes.
Saving money will depend on whether you can shop at a place where you can purchase the specialty grains in the exact quantity that you need for your recipe. If you have to continually buy your various specialty grains in one pound increments and only use 2 ounces in recipes, you're going to build up inventory that gets old and becomes a waste of money. So look for a place where you can purchase exactly the quantity that you need. Extract brewing is overall more expensive than all-grain because you're paying someone to do your mashing for you and to create a powder or syrup out of the mash run-off, but it's a time saver too. Only you can decide how valuable your time is.
Maybe different LHBS's do it differently, but with mine there is actually a cost benefit to buying the kit rather than buying the same ingredients separately. I don't do a comparison of each one that I've purchased, but I think I generally save about $5 by buying the kit vs. buying the ingredients separately. Additionally, my store gives you a homebrew kit punch card. After 10 punches, you receive a $25 gift card to the store. Which amounts to another $2.50 savings per kit.
I did a cost comparison for a friend of purchasing a kit at a local brew supply as opposed to purchasing the same ingredients separately, and there were indeed savings by purchasing the kit. The kit costs $41 (before taxes) and the ingredients cost $48.65, a savings of $7.65. However, that involved using two half-pound quantities of specialty grains (the grains are sold by the pound). If you were to purchase quantities for the equivalent of two kits, and use the half-pound quantities for each of the two kits, it would cost $46.60 per kit. Thus you would save $5.60 per kit by purchasing the kits (a saving of just over 14%).
I buy my ingredients a la cart except when a deal shows up. There was one last year during Columbus Day where Northern Brewer was selling kits for $14.92/ea. Hard to pass that up!
Even if the kit is cheaper, you still have to deal with the psychological and social ramifications of brewing a kit beer.
You will save money home brewing when you find out what malts and hops that you enjoy. Kits are fine, but you can save money if you buy certain things and aren't affraid to mix and match. Mr beer kits are too expensive. You should get a food grade plastic bucket, from somewhere, either free or cheap. Ask your local super market bakery department if they have an extra bucket.
Sometimes kits at homebrew shops are on sale. Not sure how these compare to Mr. Beer. They might save you money over buying the ingredients at the shop on a per pound / per ounce basis. You need to do the math. They likely will never save you money over buying ingredients in bulk, such as 1 lbs hop bags and 55 lb sacks of grain or food grade barrels or jerry cans of extract. As for the stigma of being a kit brewer that @Brew_Betty alludes to, I'd get over it. No different than trying a recipe that someone else made up. It's a useful model for learning what you like and can serve as a starting point for developing your own recipes if you desire.
As with all things related to brewing, you can save a small fortune buying in bulk - even if you're an extract brewer. As long as you take reasonable care to seal it up between batches (e.g. roll it up tightly and clip the bag closed w/o lots of air inside and don't store it in a damp basement), a 50 lb bag of DME will store perfectly well and costs ~ $3/lb. That's about 25% less than the going rate for 3 lb bags. I didn't brew with extract long enough to warrant a bulk extract purchase, but a friend brewed this way for years before switching to all-grain. Kits offer shopping convenience, but little else. I've never seen one that couldn't be assembled by the brewer for less a la carte.