Links as buttons with BEM; see: http://codepen.io/team/css-tricks/pen/226a65c8f7d64615aabd45048d1d3b6d

links-like-buttons.css

/* http://codepen.io/team/css-tricks/pen/226a65c8f7d64615aabd45048d1d3b6d */

/* Block */
.btn { /*  Basic Styles */ }

/* Element */
.btn__price 	{ /*  Preis */ }
.btn__text 		{ /*  Text */ }

/* Modifier */
.btn--big 		{ /*  großer Button */}

.btn--blue 		{ /*  */ }
.btn--orange 	{ /*  */ }
.btn--green 	{ /*  */ }

links-like-buttons.html

<a href="http://css-tricks.com" class="btn">
  <span class="btn__text">Standard button</span>
</a>

<a href="http://css-tricks.com" class="btn btn--orange btn--big">
  <span class="btn__price">$3</span>
  <span class="btn__text">Big button</span>
</a>

<a href="http://css-tricks.com" class="btn btn--blue btn--big">
  <span class="btn__price">$4</span>
  <span class="btn__text">Big button</span>
</a>

<a href="http://css-tricks.com" class="btn btn--green btn--big">
  <span class="btn__price">$9</span>
  <span class="btn__text">Big button</span>
</a>