You can only get v5 PS2s. You don't mention where you live and this makes a difference. If you live in a PAL region then the Messiah/Clone is the only game in town, a full no swap solution but the chip is in short supply and would retail between £70 and £90. There is also the Origachip for PAL (c. £35) which is also a full solution requiring a single swap for backups.
You didn't mention your DVD writer; that matters too as it must prduce DVD-R not DVD+R.
Different mod-chips require different boot methods. But v5 defeats many modchips including NEO2.2 and NEO4. With NEO2.5 DVD-Key life is difficult but not impossible.
If you live in an NTSC region, then the OrigaChip is the only solution for you.
www.origachip.com and forgive their bad English.