I don't know who told you the stock suspension was quite good. Could only be Triumph.
Stock is horrible. Lots of options in mid priced up to about US$600 eg Progressive 444s (that somebody recently posted a link to for under US$600), Progressive, YSS, Hagon Nitro, Ikon, and a few others and then high end options from Wilber, Racetech, Ohlins (NZ),
The cheapest Progressive 412 model and cheapest YSS are similar in grade to stock. You want their midrange or upper grade models only.