Check out your local toy store, not just the official online shop
On Reddit, there is a valuable tip from many fans in response to the question of financing: Check out the physical stores in your vicinity. Several users report that they were able to buy certain figures at a discount, often upon inquiry.
With offers, you may not always be able to specifically buy the figure you want, but you will always have the official and original packaged minis, not second-hand goods or proxies.
The online shop is convenient but always has the retail price and rarely offers discounts. In physical stores, you sometimes have the luck of encountering clearance sales or just friendly sellers who make you a special offer.
On Reddit, users also advise not to buy too much at once. Choose an army you want to play and get a few figures. Once these are assembled and painted, which can take a few weeks, you can get the next ones and have saved some money in the meantime.