If you want to compare the DeepSeek-R development costs to anything, you should be comparing it to what it cost OpenAI to develop GPT-o1 (not what they plan to spend to run it), but both numbers are somewhat irrelevant since they both build upon prior research.
Perhaps what's more relevant is that DeepSeek are not only open sourcing DeepSeek-R1, but have described in a fair bit of detail how they trained it, and how it's possible to use data generated by such a model to fine-tune a much smaller model (without needing RL) to much improve it's "reasoning" performance.
This is all raising the bar on the performance you can get for free, or run locally, which reduces what companies like OpenAI can charge for it.