What you'll find:
90% of businesses will get your email, visit your sales/landing page and if you have done your job properly will realise that they do NEED a mobile version of their website, then they will immediately call THEIR web design guy who already looks after their website and ask them to take care of it... Even if your price is way below the quote that their web guy says he can do it for because they already have a person that they know and trust.
UNLESS you pitch your email with added extra value that THEIR web guy cannot offer... Think about it.
$49 is way too cheap also. Most business owners will not want to do business with you and will not take your offer seriously.
OP paints a picture that selling mobile sites/sms is easy... It ain't! There are hundreds if not thousands of marketers already doing this and you'll find hundreds of websites offering this.
Lastly, email does work and you'll get little results. But walk-ins and cold calling work the best.