Depends on what you consider pro.
top40 hip hop, or Madlib/stones throw type vibe.
The sp404 has no way to tune/pitch samples, so you either need to do that outside the box, or find creative ways around that inside the box.
Also do you have an audio interface?
This is the extra added cost to get your beats into your computer.
sp404sx $325ish+100ish audio interface= $425
Not really the cheapest route, but not too expensive either.
A used sampler, maybe an og sp404 will run around $225, and a Zoom sampletrak even cheaper. They go for as little as $75, and are very much in the same league as an sp404 plus they can pitch samples, and sound very vintage.
The only major downside to a sampletrak is the storage is old smart media, and only accepts 16mb, or smaller cards.
The cheapest modern options are actually quite good though.
An mpd24, and an audio interface might be had for as little as $200 total.That's just $25 more than a sampletrak, and cheap audio interface.
Software giving the flexibility of an mpc4000 sampling engine is free wich is one of the nice sides of the software realm.
There is an app called Shortcircuit, and it's peerless for a free app, and competes head to head with the best comercial vst samplers.
Add in Podium free (daw sequencer), a handfull of free vst effects, and your set.
I know I just gave you more to think about, lol.
Oh, add turntable+records, and the cheaper routes start looking even better.