Vanguard reduced their initial investment requirement for Admiral shares to $3000 a little while ago. You should be able to start investing in VTSAX with $3000 now. VTSMX is just closed because it's strictly worse than VTSAX now - previously it had a worse expense ratio but a lower initial contribution amount (VTSAX used to be $10k).
First, why do you want this? Why not just use mutual funds?
If you really need ETFs for some reason, just do a set and forget into vanguard mutual funds, and convert them to the ETF share class later when you need them to be ETFs. The conversion is not a taxable event. Vanguard mutual funds are the only family which has this feature since Vanguard has a patent on it for the next several years.
Many Vanguard funds' Investor share classes were recently closed since the Admiral share classes now supersede them at the $3000 initial investment mark. Just invest in the admiral share classes (e.g. VTSAX instead of VTSMX).
Admiral shares generally have the same expense ratio as Vanguard's ETFs and neither have any fees when held at Vanguard.
I encourage you to give mutual funds a try. ETFs are overhyped in my opinion. (Probably because various institutions profit off the share creation / redemption mechanism used to fix ETF prices to the NAV on the market.)