You may try www.eLong.com
I've using this to book the tickets many time and you may paid the ticket fare by Visa in HK. Electronic Ticket can be issue immediately.
Or you may collect the paper ticket (invoice as well) as some major airport in China.
If you are in China (main city), they also can delivery the ticket to you by same day (no additional cost within city).
I've checked the flight between Wuxi and Guangzhou. You may find the below information for ref.
无锡 - 广州
出发日期:2008年01月30日
单程 最低价经济舱