What matters more to you - proximity to Moscow or price, or are both factors equally important?
If you're willing to go further from the capital, the cheapest options are usually in cities 60+ kilometers away. That includes settlements along different directions - toward Tula, Ryazan, Smolensk. There's more active development there, higher competition, and developers are forced to lower prices. Plus you can look at areas that are traditionally cheaper - for example, northeastern Moscow Region often offers more affordable apartments than the southwestern part.
But keep in mind that proximity to a commuter train station or paid highway also affects the price. If you live near an MCC station or a good road, the price is higher than if you have to walk 15 minutes from your car. Also, a lot depends right now on what benefits are available - the primary market is sometimes cheaper than the secondary market in neighboring cities, or vice versa. I'd suggest just checking a few popular real estate sites and filtering by price - that way you'll quickly figure out where it's actually cheapest right now and how far you're willing to travel.