All too true. The often recommended pirate ships and faction/deadspace mods which will do the job fast but with a significant ISK value at risk if you mess up. A less-capable standard or navy ship will do the job for less ISK risked but it will take longer. And some players do sites in lesser ships for the challenge as well, ofc. But at some point you’ll hit the limit where a cheaper ship is no longer viable. Did Lvl 3 Security missions for rep, for example, and used a Navy cruiser. Worked well, but I’m happy I switched to a BC for the bonus room in Angel Extravaganza - the cruiser (with my player skill, the character has solid fives) just couldn’t have done it.
So the question is really up to the player running a site - does he have the skills to use a lesser ship and does he feel comfortable with it?
PS: that Angel bonus room netted me a shiny Domination 50 MWD. 
