You can employ NCode system, in which total RNA is primed with universal primer then the resulting cDNA is subject to SYBR green-based qPCR with miRNA-specific primers.
You also can use miScript assay system from Qiagen. This is a SYBR green based system, where you can amplify only mature or pre-miRNA, depending on your project needs. You don't need expensive probes for this system, 3' primer is a universal primer and is a part of a kit, you can design a 5' primer yourself and order it from any company synthesizing DNA oligos, each oligo costs about 4$.
If the number of miRs you want to study is really large, you may consider microarrays (about 300€ per array with 2500+ miRs = about 0.12 €/miR and sample).