400Gb per month is sooooo much bandwith, however i cannot see any reason to need a dedicated T1 (or E1 as they are in europe) for your internet access. A co-located server an a large hosting centre would probably bet fit youre needs, as bandwith could burst at peak times (ie lunch time), as a server of that spec is capable of quite a high data throughput,well in excess of the 2.0 Mb of a dedicated E1 circuit
As an example of price, UK2 (
www.uk2.net) cost their bandwith at 99p per Gb, which is about £5k/yr + cost of server location of about £1k/yr, + cost of backup (sorry i cant estimate a price for that)
However, I do think that there would be a market for pprune subscription, where by one could pay a fixed monthly cost to have access to a less utilised server, and have less ads per page, and if possible, a low colour or text based version, of pprune, so i can read it more easly while at work
NB