If you really want a C-Store ship, I can easily recommend the Advanced Heavy Cruiser Retrofit (Excelsior) for 2000Z. Some people don't like the looks though but it is tough and the fastest cruiser. The advantage of C-Store ships is that they are also available to any alternate characters that you create.
Also consider the Mirror ships on the Exchange, some are very inexpensive. Look to STOWiki.org for the specs. The Mirror Assault Cruiser has the layout of the Assault Cruiser (3 tactical slots, etc.) but looks like the regular Star Cruiser.... so specs-wise it's a good tac cruiser. Advanced and Patrol mirror versions are also on the Exchange.
I wanted to also mention that the Advanced Heavy Cruiser Retrofit is actually an addicting ship because of the Transwarp drive. You can go almost anywhere in an instant... if you can't get there, you can get next to the sector that you want! The Transwarp drive does not take up a console/device slot either.
I like the looks of the ship because it doesn't look like a "princess" ship, it has the looks that mean business!
Please add Exploration to Star Trek Online! Are you sure it isn't time for a "colourful metaphor"? --Spock in 'The Voyage Home' Star Trek Battles Channel - Play STO more like Star Trek with challenge, teamwork and FUN!