So I have been researching DID vendors with limited success. So far my leading candidates are:

Vendor Country Set-up fee Monthly fee Per-Minute
Sonetel NL EUR 1.40 EUR 1.40 EUR 0.01
Sonetel Peru EUR 5.50 EUR 5.50 EUR 0.01
Sonetel USA EUR 0.70 EUR 0.70 EUR 0.01
twilio NL USD 1.00 USD 0.01  
twilio Peru USD 5.00 USD 0.01  
twilio USA USD 1.00 USD 0.01  
callcentric USA Free Free Free
callcentric USA USD 3.95 USD 1.95 USD 0.015
callcentric NL USD 7.95 USD 7.94 USD 0.00
callcentric Peru USD 9.95 USD11.95 USD 0.00

Note that Sonetel has a free trial number available so it would probably be better for initial set-up. The callcentric has free numbers (limited area coverage). It also has interesting phone rates for outgoing calls.