low budget and cummins do not go together , 3rd gens are going for 15k+ unless its a real clapped out xxxx. im sure you can find a deal out there , but most people know these trucks hold value due to the non emission stuff
look for a mid 2000's chevy gas with 6.0 could probably get one real cheap if you look hard enough , few yrs ago i purchased a standard cab , bare bones 2006 HD w 6.0/80e for 1200.00 192k miles no rust , super clean 1 driver company truck it had a bad direct clutch piston in the 80e , cost me 700.00 to rebuild the trans with new converter. i load the heck out of the truck and is just a work horse even with high mileage .
i do also have a 03 cummins w 6spd ill use for longer trips , but i prefer the chevy for local stuff ...... with diesels costing so much you really got to determine if its worth the extra cost to buy one just for occasional use.