I think there's a language barrier here, but I think that the problem is that the old PC doesn't have a spare PCI slot for a 100Base-T NIC. Apparently cost is an issue too.
If cost is important, I wouldn't even bother with a printer server. Even the cheapest ones, the kind that plug into the parallel port, cost quite a bit. And if it's using the parallel port, speed isn't going to increase any by plumbing it through Ethernet. So what's the point? Same thing for any USB-Ethernet adapters or USB networking stuff. Why pay lots of money for poor performance? The specs say 12MBPS, but you'd be lucky to see 6.
For the bare-bones cheapest setup, get a used ISA Ethernet card for the old PC, and buy or make a crossover cable. You'll be stuck at 10MBPS since Fast Ethernet (100MBPS) is pretty much limited to PCI cards. The good news is that you're spending £5 or so if you shop around.
A more workable setup involves making a free PCI slot. Get rid of a card, get an ISA equivalent to replace the PCI one (like a sound card), something
. Then instead of the ISA NIC get a 10/100 PCI one. You can use a crossover cable to start, or buy a hub.
If a dead uncle leaves you some cash, then get a switch. For that matter, throw out the old PC and be done with it.