Hello,
if the limit of 254 is based on the customer´s IP addressing (class C), you still could use secondary addressing on the same (Fast)Ethernet interface to extend that limit beyond the 254 clients.
If you are looking to upgrade your equipment, check out the Cisco 1841 router, which has two onboard 10/100 Ethernet ports and slots for DSL expansion. Here is the product sheet:
CISCO 1800 SERIES INTEGRATED SERVICES ROUTERS
Cisco 1800 Series Integrated Services Routers: Cisco 1841 Router (Modular)
http://www.cisco.com/en/US/products/ps5853/products_data_sheet0900aecd8016a59b.html
List price is $1,395.00...
Regards,
GP