What is your desired asset allocation? You do have one, right?
The target date funds aren't bad at all from an expense ratio perspective. You're locked into a set asset allocation with these, but Vanguard's choice here is probably pretty good for an average investor. It's important to recognize that there's no magic here, these are just a combination of a few Vanguard funds. For example, the
2055 fund that you're investing in now is:
61.6% Total Stock Market
28.3% Total International Stock Market
7.6% Total Bond Market
2.5% Total International Bond Index
Unfortunately you can't replicate this mix exactly with the individual funds in your 401(k). For example you don't have a total US stock market fund available. However you can
approximate this fund with an 81/6/13 mix of VINIX/VMICX/VSCIX, with a weighted average expense ratio of about 0.05%. You do have Vanguard's Total International Stock index fund available as well, which is nice.
The only problem is the bond allocation. There isn't a bond fund in your 401(k). You have a PIMCO bond fund and maybe some others in there too, but they all have higher expense ratios. The target retirement income fund and the closer target retirement dates are invested mostly in bonds, so you could go with one of those for bonds, or you could invest in bonds in your IRA and have all stocks in your 401(k). The IRA strategy is what I do: I invest in the best funds available in my 401(k), and then fill any gaps in my asset allocation in my IRA.
So if you did want to come as close as possible to the 2055 target date fund, and you have some money available to invest in your IRA, you would do the following:
56% Vanguard Institutional Index
4% Vanguard Mid-Cap Index
9% Vanguard Small-Cap Index
31% Vanguard International Index
Then, in your IRA you would invest the following amounts:
8% of your 401(k) balance in Vanguard Total Bond Index
3% of your 401(k) balance in Vanguard International Bond Index
Or you could just pay an extra 0.1% expense ratio and not mess with it.