Marketing is important, even more so than before in my opinion. Look at artists like One Direction, a group of talented boys but nothing special... then look at the hysteria that surrounds them, Justin Bieber is another good example.
The song "Call Me Maybe" is a perfect example. That song was released almost one year ago, but how many people had heard of it? Maybe a few thousand. Then Carly Rae Jepsen signs to the label ran by Justin Biebers manager earlier this year... now it has over 220,000,000 youtube views and almost everyone that pays attention to popular culture can recite the lyrics.
Marketing is everything. Sure it's not always traditional marketing -- billboards, tv spots -- but using existing artists too. Carly Rae Jepsen is famous because of Justin Biebers marketing power.
If it wasn't for marketing, your friends would not have likely heard of them in order to recommend them to you. Marketing is more than just MTV and radio. That viral YouTube link you sent out was most likely started by someone in the music industry. That indie band? You know of them because someone marketed them.
As of 2010, these are the line items on a budget to release a major label record. The same (minus a few things) applies to indies.
PROMOTION:
Indie promo (paying someone to promote to radio)
Tip sheets (newsletter advertising)
Radio promo contests (those win-it-before-you-can-buy-it and fly-aways)
Radio marketing (ads)
^ the above breaks down by format. Formats are:
Alternative, Active/AOR/Rock, College, AAA, Specialty Format (ie, Urban).
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MISC PROMOTION:
Radio shows (including artist travel, accommodations, etc)
Promotion CD's
Tip sheet design and prep
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SALES:
Advertisement placements (ie, circulars, endcaps)
Retail Marketing
Outside retail marketing
Retail merch admats
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ADVERTISING:
Print
TV
Radio
Online
Outdoor/sniping
Circulars
Prep and art production
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STREET MARKETING
Merch
Promotions
Outside street team
Samplers
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MISC MARKETING:
Advances, DJ advances
Remixes
General merch (ie, those funky things artists do to promote records)
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PUBLICITY
Indie publicists (if the artist doesn't use the staff)
TV appearances (travel, etc)
Photo shoots
Press travel
Tour logistics (aka Artist Development)
Prints, bios, misc (copywriters, etc)
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VIDEO:
Video production
Live footage, EPK cuts
VIDEO PROMOTION:
Video indies
Video promotions
Video duplication
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TOURING:
Tour support
Tour marketing
Promo tours (including setup, crew, backline, travel)
Ticket buys (from the venues, these aren't free!)
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ONLINE
Marketing
Website tech cost
Website design
Other tech (Facebook, widgets, games, Lee Martin)
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PACKAGING
Art
Production
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INTERNATIONAL MARKETING
Tour support
Promo tour
Publicity
Production
Misc
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* Some of these aren't done. Some are much more expensive than others. Anyhow, a lot to be said about this but that's worthy of a blog post.
Also this has likely changed a bit recently.