You could try look at Toyota's website, where you can compare the current versions (see http://www.toyota.co.uk/cgi-bin/toyota/bv/generic_editorial.jsp?deepLink=YA4_Equipment_new&nodiv=TRUE&fullwidth=TRUE&edname=YA4_equipment&zone=Zone%20NG%20Yaris&navRoot=toyota_1024_root ) or request a brochure (see https://www.toyota.co.uk/cgi-bin/toyota/bv/leads/brochure/email_brochure1.jsp?range=YA4&zone=Zone+NG+Yaris&BV_UseBVCookie=yes&navRoot=toyota_1024_root&selectedBrochures=rc5560&redirect=true )
For used versions, the best resource is probably Parkers (see http://www.parkers.co.uk/cars/equipment/Summary.aspx?model=1447 )