I'm not finding it easy using the net here in Thailand to find out where I can buy a used backhoe near or in Udon Thani, or anything for that matter.

The internet isnt anywhere as helpful here in Thailand even with my
Thai girlfriend searching in Thai.

Quoting me 100 baht for a meter of backhoe work making a drain, or 15000 baht for 1 day is a rip off. Back home, $300 (9000 baht) hire for a weekend, and that's Western prices.

Anyone know a more reasonable price to hire or where to buy a 1 tonne backhoe.

Thanks.

Seems like you might be asking the wrong person.  I'd go to your local Hardware House or Global House and see if they can help.  They might give you a good reference???