Well, here are my thoughts:

1. The 1200dpi is worth it if you can swing it.
2. The "d" option (duplex) adds a lot to the price. I don't think that double-sided printing is a big deal. As others have said, most software supports printing every other page and then reloading the paper.
3. The only difference between the 2420 vs. the 2430 is throughput, and going the 2420 route saves you money.
4. You might be able to find a new 2300 or 2200 series on ebay. There was a brand new 2300dn for US$379.
5. I have a spare JetDirect card (the network print server card that makes the printer an "N") that you can have, but we'll need to make sure my model is compatible with the printer you buy.
6. The paper path is not straight on the 2xxx series, but I have sucessfully printed on cardstock.

If I were you, I really wouldn't consider anything other than an HP. Drivers, reliability, performance, postscript support, multiple OS support -- everything points to HP. The exception, of course, is price per page. For home use, however, I feel that features and performance outweigh cost/page. If you were using it in an office and printing lots of reports, well, that's different.

That said, if you don't want to go for a 2200 or 2300 or try to find a refurbished or cheap 24xx, I would definitely get an HP one model lower.

Finally, I can buy here and ship it to you, if you would like my help. I imagine that is pretty expensive, but it might save you some money overall. There may be mains power issues with that also...

FWIW,

Jim