Not really. You can pay anyone to be on your track, and indie artists don't charge much. Pras appeared on one of our songs on our last album for free because we have the same management and my cousin produced a track for his album in return. But I know how much he charges other artists for a guest appearance. And it's much more than what KGR and Canibus charge. They aren't major label artists.
My manager also manages Lauryn Hill. Even she has a price and she's sold over 15 million records. But, pretty much nobody can afford what she asks. Joss Stone got Lauryn on a track a few years back and spent her entire album budget on it pretty much. And Joss has sold a few million herself, so she gets big budgets from her label.
A good friend of mine had Beenie Man, Twista, Sean Paul and DMX on his album. I know how much they all charge. And it's less than you would think, and they ARE major label artists. You can only quantify success through associations with other artists to people who don't know any better and don't know how this industry works.
A better way to quantify success is through touring. I'll give you a real world example. A typical leg (ie, one part) of an international tour for me and my band tends to be about 6 shows. That's two weeks minimum, three if you only want to play weekend dates which depends on the culture and the cities you're hitting. 8 people on the tour including band, management, and tour manager. First class return air flights. 5 star hotels. Per Diems (daily money the promoters give you for your own personal use). Vehicle rental. And performance fee on top of that. Combine that with the costs the promoter has of creating the gig in the first place. Hiring the venue, hiring the equipment, etc, etc. Giving a cut to Ticketmaster. That's a SERIOUS investment. It's more than what most banks will give to people starting businesses. And it's dozens of times more than what someone like KGR would charge for a verse. Most years we do at least 3 tours like that. In a release year, it's 5 or 6. Even a lot of artists who you would think are REALLY well known aren't doing international tours because they don't have a sufficient international fanbase to make promoters wanna make that investment unless there's big corporate backing.
If you're doing tours like that, you're a success. Hell, if you're doing international tours at all, you're a success because at the very least you're worth economy flights, a decent hotel and a performance fee. I know some artists that are extremely talented, have sold tens of thousands of records, have had decent radio exposure in the UK, have a solid fanbase, and they still can't get booked for a single gig outside of their home country.
A few thousand hits on your myspace page, some local club shows and some C-List rappers on your song does not equal big star.