No there aren't. The budget airlines based up north mainly services destinations in China instead. TR flies to Macau and the tix can be quite cheap when there's a promotion, but the problem is that the ferry ticket from Macau to Hong Kong is quite expensive and takes one hour.
So far, I noticed that the cheapest airfare is still offered by Jetstar Asia, followed by United Airlines, Cathay Pacific and finally Singapore Airlines. China Airlines used to be the same price or even cheaper than Jetstar Asia at times (perhaps cos of the unfavourable timings), but they had suspended the SIN-HKG route wef 26 Jun 06.
heard that jetstar is quite good, 20kg baggage allowance also.
personally, i dun find the Cathay Pacific service or inflight meals fantastic - soS doesnt justify the extra $$$ - i rather u spend it on getting some camera stuff in HK
SQ also standard dropping leh, it seems, the other day i took SQ to Shanghai, the movies/music-on demand system was down for the entire flight...so couuld only watch those broadcasted ones..which i didn't really enjoy.