I've been using DSP Quattro for a few years (http://www.dsp-quattro.com/) and it works quite well. Authoring CDs is easy, though they need to incorporate a single keystroke shortcut to add a CD track.
I may try out Triumph though, just to see if it has any advantages over Quattro (http://triumph.aurchitect.com/)
One that I have tried out recently is DSP Quattro and I think its only about £80 or so. Its a nice simple layout for mastering, you can also use it for all the tracks on the album (set them up in the order you want) and add transitions/seperate effects to each track. I think it comes with some stock plugins (anyone correct me if Im wrong) but If you have the money I'd advise researching and finding a few plugins that suit your needs. For mastering essentially you can do just as much with an EQ, Limiter, and Compression if you research how to use them properly. Maybe some multi band dynamics as well. Just keep in mind that subtle adjustments can have a better effect than big adjustments and make sure you have a reason for example, adding compression, rather than just doing it because you read somewhere that "thats the only way to do it". Keep in mind that every track is different. Have a look at Brainworx bx_digital V2. Its a great EQ that allows you to EQ mid/side, worth the investment.
http://www.dsp-quattro.com/dspquattro/Site/DSP-Quattro.html http://www.brainworx-music.de/en/plugins/bx_digital_v2