It's worth noting sampling hasn't really got saxophones down very well. It's a crazily personal instrument. A friend who is totally unmusical got told to invest in old saxophones and collected dozens at all prices. When I found out I went along and played them. My modest playing in just a few puffs put loads into the rubbish category - a few into excellent and a lot into middle ground. He even had a couple of duplicates Two seller Mk 6's - one was absolutely great sounding and so easy to play. The other, identical, needed much more player ability than I have. Every single one sounded wildly different. Couple this with every player's different technique and it's a sampler nightmare. You play the notes, but even with a couple of continuous controllers, I cannot replicate the sound of a jazzy sax. You can't growl or sing or speak, because that's unique to the song and impossible to synthesise or sample in a meaningful way. The Spitfire brass I have is the best sounding ensemble - but it's saxes are not as good as trumpet and trombone. I do have a cheap VSTi called sensual sax - that has a control called sex - and it can sometimes really work - but it's very unpredictable when you push it. Hidden in a mix with just a few little phrases I can get away with it - but my guitars and basses tend to stay on the hangers and the three saxes get use with mics. I'm a crap trumpet player, but still have one I can use for little stabby bits sometimes. Many sax samples sound like kazoos - I've some great Garritan packages but they are like Spitfire - a bit weak with saxes. It's not their fault - it's just a very difficult instrument to reproduce.
If you are just doing "stabs" then you should be ok with spitfire or some samples, As Rob has pointed out, solo sax performance can be problematic, not only because of individual instruments such as Selmer sounding different from low priced examples; there are Soprano. Alto, Tenor and Bass versions, but also the fact that different mouth pieces sound differently, and the sax is not fully a brass instrument since it uses a reed to create sound rather than a metal mouthpiece. Sort of a cross between brass and reed. I would consider using trombone in any planned "horn" section stabs, and mix any sax parts lower to keep the lack of a live instrument from sticking out. Think Phil Collins type "horn" parts. Good solo sax sounds probably are going to be something for the full version of NI's Kontakt and will most likely be pricey. I recommend keeping it simple
I heard a fellow who could do a really good sax with a digital keyboard. The trick was that he used the pitch wheel a LOT to add the slurs and vibrato that a sax player does. Just playing the notes on a plain keyboard didn't sound realistic at all, even though it was the exact same instrument.
Thanks for all your advice guys. I don't know squad about brass instruments it seems The idea that I have is using a mix of a melody like the sax in 'the man with a red face' by Laurent garnier and a Angie stone song called 'I wish I didn't miss you'
I assume you meant 'squat'.
But not knowing much about brass instruments may turn out to be a positive advantage for you.
I've found in my stuff, because I don't really know how orchestrators score brass, I utilize the various instruments how I want them to be and to me, it often comes over as very original and unusual.
Maybe not good, but original and unusual !
At present, my best sax and non-orchestral brass instruments are in Kontakt libraries and, unfortunately for your "inexpensive" qualification, mostly for the full version of Kontakt and not the free Player version. What Rob Aylestone posted above is very telling about sax libraries and I'd add that some sound very synthetic throughout their entire range, some sound good within a given range, some can do some things better than an accomplished (maybe any) player can, many can sound good mixed in a section but not so good solo, they're getting better, and, not surprisingly, none appear to be as facile or versatile as an actual player---so, what TalismanRich alluded to really applies: it takes work and skill to use a sax library to get a realistic sound, especially as a solo/feature instrument.
All that being said, your least expensive alternatives might be free online loops and/or loop/sound services like Arcade, sounds.com, loopcloud, etc.