There was tourist information office (call: +370 318 51160) located in the Town Hall building (when you enter on the right). Where it was? At main town sqaure - Nepriklausomybes aikste, on the left side driving Highway 134 from Kalvarija towards Veisiejai and Druskininkai.
They offered good maps of Lithuania, its some regions and cities and some leaflets on the area but... read in my tourist trap tips.
Some, but not complete, information is available via internet:
History of Lazdijai
Well, there were stores in Lazdijai which didn't accept any debit/credit cards. Just in case you need some cash... look for this kiosk on my picture.
There was 24 h open ATM cash inside which accepted cards of Visa and Eurocard/Mastercard. The kiosk - Bankas SNORAS - stood at the main town square: Nepriklausomybes aikste.